v1 --> v2:
1. Cleanup sparse warnings.
Zhen Lei (2):
ARM: Fix some check warnings of tool sparse
ARM: Make the dumped instructions are consistent with the disassembled
ones
arch/arm/kernel/traps.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
--
2.25.1
Fix the following warnings:
warning: incorrect type in initializer (different address spaces)
expected unsigned short [noderef] __user *register __p
got unsigned short [usertype] *
warning: cast removes address space '__user' of expression
Signed-off-by: Zhen Lei <[email protected]>
---
arch/arm/kernel/traps.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 20b2db6dcd1ced7..34aa80c09c508c1 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -188,9 +188,9 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
}
} else {
if (thumb)
- bad = get_user(val, &((u16 *)addr)[i]);
+ bad = get_user(val, &((u16 __user *)addr)[i]);
else
- bad = get_user(val, &((u32 *)addr)[i]);
+ bad = get_user(val, &((u32 __user *)addr)[i]);
}
if (!bad)
@@ -455,15 +455,15 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
if (processor_mode(regs) == SVC_MODE) {
#ifdef CONFIG_THUMB2_KERNEL
if (thumb_mode(regs)) {
- instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
+ instr = __mem_to_opcode_thumb16(((__force u16 *)pc)[0]);
if (is_wide_instruction(instr)) {
u16 inst2;
- inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
+ inst2 = __mem_to_opcode_thumb16(((__force u16 *)pc)[1]);
instr = __opcode_thumb32_compose(instr, inst2);
}
} else
#endif
- instr = __mem_to_opcode_arm(*(u32 *) pc);
+ instr = __mem_to_opcode_arm(*(__force u32 *) pc);
} else if (thumb_mode(regs)) {
if (get_user(instr, (u16 __user *)pc))
goto die_sig;
--
2.25.1
On Mon, 10 Oct 2022 at 11:56, Zhen Lei <[email protected]> wrote:
>
> Fix the following warnings:
> warning: incorrect type in initializer (different address spaces)
> expected unsigned short [noderef] __user *register __p
> got unsigned short [usertype] *
> warning: cast removes address space '__user' of expression
>
> Signed-off-by: Zhen Lei <[email protected]>
> ---
> arch/arm/kernel/traps.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
> index 20b2db6dcd1ced7..34aa80c09c508c1 100644
> --- a/arch/arm/kernel/traps.c
> +++ b/arch/arm/kernel/traps.c
> @@ -188,9 +188,9 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
> }
> } else {
> if (thumb)
> - bad = get_user(val, &((u16 *)addr)[i]);
> + bad = get_user(val, &((u16 __user *)addr)[i]);
> else
> - bad = get_user(val, &((u32 *)addr)[i]);
> + bad = get_user(val, &((u32 __user *)addr)[i]);
> }
>
> if (!bad)
> @@ -455,15 +455,15 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
> if (processor_mode(regs) == SVC_MODE) {
> #ifdef CONFIG_THUMB2_KERNEL
> if (thumb_mode(regs)) {
> - instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
> + instr = __mem_to_opcode_thumb16(((__force u16 *)pc)[0]);
Shouldn't this be __user as well? (and below)
> if (is_wide_instruction(instr)) {
> u16 inst2;
> - inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
> + inst2 = __mem_to_opcode_thumb16(((__force u16 *)pc)[1]);
> instr = __opcode_thumb32_compose(instr, inst2);
> }
> } else
> #endif
> - instr = __mem_to_opcode_arm(*(u32 *) pc);
> + instr = __mem_to_opcode_arm(*(__force u32 *) pc);
> } else if (thumb_mode(regs)) {
> if (get_user(instr, (u16 __user *)pc))
> goto die_sig;
> --
> 2.25.1
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
On Mon, 10 Oct 2022 at 12:58, Leizhen (ThunderTown)
<[email protected]> wrote:
>
>
>
> On 2022/10/10 18:20, Ard Biesheuvel wrote:
> > On Mon, 10 Oct 2022 at 11:56, Zhen Lei <[email protected]> wrote:
> >>
> >> Fix the following warnings:
> >> warning: incorrect type in initializer (different address spaces)
> >> expected unsigned short [noderef] __user *register __p
> >> got unsigned short [usertype] *
> >> warning: cast removes address space '__user' of expression
> >>
> >> Signed-off-by: Zhen Lei <[email protected]>
> >> ---
> >> arch/arm/kernel/traps.c | 10 +++++-----
> >> 1 file changed, 5 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
> >> index 20b2db6dcd1ced7..34aa80c09c508c1 100644
> >> --- a/arch/arm/kernel/traps.c
> >> +++ b/arch/arm/kernel/traps.c
> >> @@ -188,9 +188,9 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
> >> }
> >> } else {
> >> if (thumb)
> >> - bad = get_user(val, &((u16 *)addr)[i]);
> >> + bad = get_user(val, &((u16 __user *)addr)[i]);
> >> else
> >> - bad = get_user(val, &((u32 *)addr)[i]);
> >> + bad = get_user(val, &((u32 __user *)addr)[i]);
> >> }
> >>
> >> if (!bad)
> >> @@ -455,15 +455,15 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
> >> if (processor_mode(regs) == SVC_MODE) {
> >> #ifdef CONFIG_THUMB2_KERNEL
> >> if (thumb_mode(regs)) {
> >> - instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
> >> + instr = __mem_to_opcode_thumb16(((__force u16 *)pc)[0]);
> >
> > Shouldn't this be __user as well? (and below)
>
> unsigned int instr;
> void __user *pc;
>
> The __user can clear the warning, but a new warning will be generated.
>
> instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
> ^new ^old
>
> arch/arm/kernel/traps.c:473:33: warning: dereference of noderef expression
>
This is because dereferencing a __user pointer is not permitted.
So this code should be using get_kernel_nofault() here not a plain
dereference of PC. So better to fix that properly instead of papering
over it with a __force cast just to make sparse happy.
> >
> >> if (is_wide_instruction(instr)) {
> >> u16 inst2;
> >> - inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
> >> + inst2 = __mem_to_opcode_thumb16(((__force u16 *)pc)[1]);
> >> instr = __opcode_thumb32_compose(instr, inst2);
> >> }
> >> } else
> >> #endif
> >> - instr = __mem_to_opcode_arm(*(u32 *) pc);
> >> + instr = __mem_to_opcode_arm(*(__force u32 *) pc);
> >> } else if (thumb_mode(regs)) {
> >> if (get_user(instr, (u16 __user *)pc))
> >> goto die_sig;
> >> --
> >> 2.25.1
> >>
> >>
> >> _______________________________________________
> >> linux-arm-kernel mailing list
> >> [email protected]
> >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> > .
> >
>
> --
> Regards,
> Zhen Lei
On 2022/10/10 18:20, Ard Biesheuvel wrote:
> On Mon, 10 Oct 2022 at 11:56, Zhen Lei <[email protected]> wrote:
>>
>> Fix the following warnings:
>> warning: incorrect type in initializer (different address spaces)
>> expected unsigned short [noderef] __user *register __p
>> got unsigned short [usertype] *
>> warning: cast removes address space '__user' of expression
>>
>> Signed-off-by: Zhen Lei <[email protected]>
>> ---
>> arch/arm/kernel/traps.c | 10 +++++-----
>> 1 file changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
>> index 20b2db6dcd1ced7..34aa80c09c508c1 100644
>> --- a/arch/arm/kernel/traps.c
>> +++ b/arch/arm/kernel/traps.c
>> @@ -188,9 +188,9 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
>> }
>> } else {
>> if (thumb)
>> - bad = get_user(val, &((u16 *)addr)[i]);
>> + bad = get_user(val, &((u16 __user *)addr)[i]);
>> else
>> - bad = get_user(val, &((u32 *)addr)[i]);
>> + bad = get_user(val, &((u32 __user *)addr)[i]);
>> }
>>
>> if (!bad)
>> @@ -455,15 +455,15 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
>> if (processor_mode(regs) == SVC_MODE) {
>> #ifdef CONFIG_THUMB2_KERNEL
>> if (thumb_mode(regs)) {
>> - instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
>> + instr = __mem_to_opcode_thumb16(((__force u16 *)pc)[0]);
>
> Shouldn't this be __user as well? (and below)
unsigned int instr;
void __user *pc;
The __user can clear the warning, but a new warning will be generated.
instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
^new ^old
arch/arm/kernel/traps.c:473:33: warning: dereference of noderef expression
>
>> if (is_wide_instruction(instr)) {
>> u16 inst2;
>> - inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
>> + inst2 = __mem_to_opcode_thumb16(((__force u16 *)pc)[1]);
>> instr = __opcode_thumb32_compose(instr, inst2);
>> }
>> } else
>> #endif
>> - instr = __mem_to_opcode_arm(*(u32 *) pc);
>> + instr = __mem_to_opcode_arm(*(__force u32 *) pc);
>> } else if (thumb_mode(regs)) {
>> if (get_user(instr, (u16 __user *)pc))
>> goto die_sig;
>> --
>> 2.25.1
>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> [email protected]
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> .
>
--
Regards,
Zhen Lei
On Mon, Oct 10, 2022 at 01:06:19PM +0200, Ard Biesheuvel wrote:
> On Mon, 10 Oct 2022 at 12:58, Leizhen (ThunderTown)
> <[email protected]> wrote:
> >
> >
> >
> > On 2022/10/10 18:20, Ard Biesheuvel wrote:
> > > On Mon, 10 Oct 2022 at 11:56, Zhen Lei <[email protected]> wrote:
> > >>
> > >> Fix the following warnings:
> > >> warning: incorrect type in initializer (different address spaces)
> > >> expected unsigned short [noderef] __user *register __p
> > >> got unsigned short [usertype] *
> > >> warning: cast removes address space '__user' of expression
> > >>
> > >> Signed-off-by: Zhen Lei <[email protected]>
> > >> ---
> > >> arch/arm/kernel/traps.c | 10 +++++-----
> > >> 1 file changed, 5 insertions(+), 5 deletions(-)
> > >>
> > >> diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
> > >> index 20b2db6dcd1ced7..34aa80c09c508c1 100644
> > >> --- a/arch/arm/kernel/traps.c
> > >> +++ b/arch/arm/kernel/traps.c
> > >> @@ -188,9 +188,9 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
> > >> }
> > >> } else {
> > >> if (thumb)
> > >> - bad = get_user(val, &((u16 *)addr)[i]);
> > >> + bad = get_user(val, &((u16 __user *)addr)[i]);
> > >> else
> > >> - bad = get_user(val, &((u32 *)addr)[i]);
> > >> + bad = get_user(val, &((u32 __user *)addr)[i]);
> > >> }
> > >>
> > >> if (!bad)
> > >> @@ -455,15 +455,15 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
> > >> if (processor_mode(regs) == SVC_MODE) {
> > >> #ifdef CONFIG_THUMB2_KERNEL
> > >> if (thumb_mode(regs)) {
> > >> - instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
> > >> + instr = __mem_to_opcode_thumb16(((__force u16 *)pc)[0]);
> > >
> > > Shouldn't this be __user as well? (and below)
> >
> > unsigned int instr;
> > void __user *pc;
> >
> > The __user can clear the warning, but a new warning will be generated.
> >
> > instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
> > ^new ^old
> >
> > arch/arm/kernel/traps.c:473:33: warning: dereference of noderef expression
> >
>
> This is because dereferencing a __user pointer is not permitted.
>
> So this code should be using get_kernel_nofault() here not a plain
> dereference of PC. So better to fix that properly instead of papering
> over it with a __force cast just to make sparse happy.
Why? We won't get here unless the PC can be dereferenced. If it's not
able to be dereferenced, then we'd be dealing with a prefetch abort.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
On Mon, Oct 10, 2022 at 05:53:45PM +0800, Zhen Lei wrote:
> Fix the following warnings:
> warning: incorrect type in initializer (different address spaces)
> expected unsigned short [noderef] __user *register __p
> got unsigned short [usertype] *
> warning: cast removes address space '__user' of expression
I have a general principle that not all warnings should be fixed,
especially when it comes to sparse.
The aim is not to get to zero warnings - it's to get to a point where
the code is correct, and plastering the code with __force casts means
it isn't correct - you're just masking the warning.
So no, I really don't like this. And I really don't like seeing
__force being used in open code in casts.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
On Mon, Oct 10, 2022 at 06:14:56PM +0200, Ard Biesheuvel wrote:
> On Mon, 10 Oct 2022 at 18:08, Russell King (Oracle)
> <[email protected]> wrote:
> >
> > On Mon, Oct 10, 2022 at 01:06:19PM +0200, Ard Biesheuvel wrote:
> > > On Mon, 10 Oct 2022 at 12:58, Leizhen (ThunderTown)
> > > <[email protected]> wrote:
> > > >
> > > >
> > > >
> > > > On 2022/10/10 18:20, Ard Biesheuvel wrote:
> > > > > On Mon, 10 Oct 2022 at 11:56, Zhen Lei <[email protected]> wrote:
> > > > >>
> > > > >> Fix the following warnings:
> > > > >> warning: incorrect type in initializer (different address spaces)
> > > > >> expected unsigned short [noderef] __user *register __p
> > > > >> got unsigned short [usertype] *
> > > > >> warning: cast removes address space '__user' of expression
> > > > >>
> > > > >> Signed-off-by: Zhen Lei <[email protected]>
> > > > >> ---
> > > > >> arch/arm/kernel/traps.c | 10 +++++-----
> > > > >> 1 file changed, 5 insertions(+), 5 deletions(-)
> > > > >>
> > > > >> diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
> > > > >> index 20b2db6dcd1ced7..34aa80c09c508c1 100644
> > > > >> --- a/arch/arm/kernel/traps.c
> > > > >> +++ b/arch/arm/kernel/traps.c
> > > > >> @@ -188,9 +188,9 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
> > > > >> }
> > > > >> } else {
> > > > >> if (thumb)
> > > > >> - bad = get_user(val, &((u16 *)addr)[i]);
> > > > >> + bad = get_user(val, &((u16 __user *)addr)[i]);
> > > > >> else
> > > > >> - bad = get_user(val, &((u32 *)addr)[i]);
> > > > >> + bad = get_user(val, &((u32 __user *)addr)[i]);
> > > > >> }
> > > > >>
> > > > >> if (!bad)
> > > > >> @@ -455,15 +455,15 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
> > > > >> if (processor_mode(regs) == SVC_MODE) {
> > > > >> #ifdef CONFIG_THUMB2_KERNEL
> > > > >> if (thumb_mode(regs)) {
> > > > >> - instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
> > > > >> + instr = __mem_to_opcode_thumb16(((__force u16 *)pc)[0]);
> > > > >
> > > > > Shouldn't this be __user as well? (and below)
> > > >
> > > > unsigned int instr;
> > > > void __user *pc;
> > > >
> > > > The __user can clear the warning, but a new warning will be generated.
> > > >
> > > > instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
> > > > ^new ^old
> > > >
> > > > arch/arm/kernel/traps.c:473:33: warning: dereference of noderef expression
> > > >
> > >
> > > This is because dereferencing a __user pointer is not permitted.
> > >
> > > So this code should be using get_kernel_nofault() here not a plain
> > > dereference of PC. So better to fix that properly instead of papering
> > > over it with a __force cast just to make sparse happy.
> >
> > Why? We won't get here unless the PC can be dereferenced. If it's not
> > able to be dereferenced, then we'd be dealing with a prefetch abort.
> >
>
> If that is guaranteed (i.e., there is no way we might be racing with a
> module unload on another CPU or something like that), then I agree
> that dereferencing PC is fine.
If we get here for an instruction in a module that's being unloaded, we
have way bigger problems. We shouldn't be executing code in a module
being unloaded in the first place. That becomes a case of "deserves to
oops".
The more likely case would be a prefetch abort when the page is
unmapped. You'd have to try pretty hard to get an undef to race with
a module unload.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
On Mon, 10 Oct 2022 at 18:08, Russell King (Oracle)
<[email protected]> wrote:
>
> On Mon, Oct 10, 2022 at 01:06:19PM +0200, Ard Biesheuvel wrote:
> > On Mon, 10 Oct 2022 at 12:58, Leizhen (ThunderTown)
> > <[email protected]> wrote:
> > >
> > >
> > >
> > > On 2022/10/10 18:20, Ard Biesheuvel wrote:
> > > > On Mon, 10 Oct 2022 at 11:56, Zhen Lei <[email protected]> wrote:
> > > >>
> > > >> Fix the following warnings:
> > > >> warning: incorrect type in initializer (different address spaces)
> > > >> expected unsigned short [noderef] __user *register __p
> > > >> got unsigned short [usertype] *
> > > >> warning: cast removes address space '__user' of expression
> > > >>
> > > >> Signed-off-by: Zhen Lei <[email protected]>
> > > >> ---
> > > >> arch/arm/kernel/traps.c | 10 +++++-----
> > > >> 1 file changed, 5 insertions(+), 5 deletions(-)
> > > >>
> > > >> diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
> > > >> index 20b2db6dcd1ced7..34aa80c09c508c1 100644
> > > >> --- a/arch/arm/kernel/traps.c
> > > >> +++ b/arch/arm/kernel/traps.c
> > > >> @@ -188,9 +188,9 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
> > > >> }
> > > >> } else {
> > > >> if (thumb)
> > > >> - bad = get_user(val, &((u16 *)addr)[i]);
> > > >> + bad = get_user(val, &((u16 __user *)addr)[i]);
> > > >> else
> > > >> - bad = get_user(val, &((u32 *)addr)[i]);
> > > >> + bad = get_user(val, &((u32 __user *)addr)[i]);
> > > >> }
> > > >>
> > > >> if (!bad)
> > > >> @@ -455,15 +455,15 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
> > > >> if (processor_mode(regs) == SVC_MODE) {
> > > >> #ifdef CONFIG_THUMB2_KERNEL
> > > >> if (thumb_mode(regs)) {
> > > >> - instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
> > > >> + instr = __mem_to_opcode_thumb16(((__force u16 *)pc)[0]);
> > > >
> > > > Shouldn't this be __user as well? (and below)
> > >
> > > unsigned int instr;
> > > void __user *pc;
> > >
> > > The __user can clear the warning, but a new warning will be generated.
> > >
> > > instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
> > > ^new ^old
> > >
> > > arch/arm/kernel/traps.c:473:33: warning: dereference of noderef expression
> > >
> >
> > This is because dereferencing a __user pointer is not permitted.
> >
> > So this code should be using get_kernel_nofault() here not a plain
> > dereference of PC. So better to fix that properly instead of papering
> > over it with a __force cast just to make sparse happy.
>
> Why? We won't get here unless the PC can be dereferenced. If it's not
> able to be dereferenced, then we'd be dealing with a prefetch abort.
>
If that is guaranteed (i.e., there is no way we might be racing with a
module unload on another CPU or something like that), then I agree
that dereferencing PC is fine.
On 2022/10/10 19:06, Ard Biesheuvel wrote:
> On Mon, 10 Oct 2022 at 12:58, Leizhen (ThunderTown)
> <[email protected]> wrote:
>>
>>
>>
>> On 2022/10/10 18:20, Ard Biesheuvel wrote:
>>> On Mon, 10 Oct 2022 at 11:56, Zhen Lei <[email protected]> wrote:
>>>>
>>>> Fix the following warnings:
>>>> warning: incorrect type in initializer (different address spaces)
>>>> expected unsigned short [noderef] __user *register __p
>>>> got unsigned short [usertype] *
>>>> warning: cast removes address space '__user' of expression
>>>>
>>>> Signed-off-by: Zhen Lei <[email protected]>
>>>> ---
>>>> arch/arm/kernel/traps.c | 10 +++++-----
>>>> 1 file changed, 5 insertions(+), 5 deletions(-)
>>>>
>>>> diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
>>>> index 20b2db6dcd1ced7..34aa80c09c508c1 100644
>>>> --- a/arch/arm/kernel/traps.c
>>>> +++ b/arch/arm/kernel/traps.c
>>>> @@ -188,9 +188,9 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
>>>> }
>>>> } else {
>>>> if (thumb)
>>>> - bad = get_user(val, &((u16 *)addr)[i]);
>>>> + bad = get_user(val, &((u16 __user *)addr)[i]);
>>>> else
>>>> - bad = get_user(val, &((u32 *)addr)[i]);
>>>> + bad = get_user(val, &((u32 __user *)addr)[i]);
>>>> }
>>>>
>>>> if (!bad)
>>>> @@ -455,15 +455,15 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
>>>> if (processor_mode(regs) == SVC_MODE) {
>>>> #ifdef CONFIG_THUMB2_KERNEL
>>>> if (thumb_mode(regs)) {
>>>> - instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
>>>> + instr = __mem_to_opcode_thumb16(((__force u16 *)pc)[0]);
>>>
>>> Shouldn't this be __user as well? (and below)
>>
>> unsigned int instr;
>> void __user *pc;
>>
>> The __user can clear the warning, but a new warning will be generated.
>>
>> instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
>> ^new ^old
>>
>> arch/arm/kernel/traps.c:473:33: warning: dereference of noderef expression
>>
>
> This is because dereferencing a __user pointer is not permitted.
>
> So this code should be using get_kernel_nofault() here not a plain
> dereference of PC. So better to fix that properly instead of papering
> over it with a __force cast just to make sparse happy.
How about:
@@ -451,9 +451,9 @@ int call_undef_hook(struct pt_regs *regs, unsigned int instr)
asmlinkage void do_undefinstr(struct pt_regs *regs)
{
unsigned int instr;
- void __user *pc;
+ void *pc;
- pc = (void __user *)instruction_pointer(regs);
+ pc = (void *)instruction_pointer(regs);
if (processor_mode(regs) == SVC_MODE) {
#ifdef CONFIG_THUMB2_KERNEL
@@ -497,7 +497,7 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
}
#endif
arm_notify_die("Oops - undefined instruction", regs,
- SIGILL, ILL_ILLOPC, pc, 0, 6);
+ SIGILL, ILL_ILLOPC, (void __user *)pc, 0, 6);
}
NOKPROBE_SYMBOL(do_undefinstr)
The 'pc' may come from kernel or user. And I found that all the get_user()
calls have already done type casts to the pc, except arm_notify_die().
I think the above changes are reasonable.
>
>
>>>
>>>> if (is_wide_instruction(instr)) {
>>>> u16 inst2;
>>>> - inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
>>>> + inst2 = __mem_to_opcode_thumb16(((__force u16 *)pc)[1]);
>>>> instr = __opcode_thumb32_compose(instr, inst2);
>>>> }
>>>> } else
>>>> #endif
>>>> - instr = __mem_to_opcode_arm(*(u32 *) pc);
>>>> + instr = __mem_to_opcode_arm(*(__force u32 *) pc);
>>>> } else if (thumb_mode(regs)) {
>>>> if (get_user(instr, (u16 __user *)pc))
>>>> goto die_sig;
>>>> --
>>>> 2.25.1
>>>>
>>>>
>>>> _______________________________________________
>>>> linux-arm-kernel mailing list
>>>> [email protected]
>>>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>> .
>>>
>>
>> --
>> Regards,
>> Zhen Lei
> .
>
--
Regards,
Zhen Lei
On 2022/10/11 0:05, Russell King (Oracle) wrote:
> On Mon, Oct 10, 2022 at 05:53:45PM +0800, Zhen Lei wrote:
>> Fix the following warnings:
>> warning: incorrect type in initializer (different address spaces)
>> expected unsigned short [noderef] __user *register __p
>> got unsigned short [usertype] *
>> warning: cast removes address space '__user' of expression
>
> I have a general principle that not all warnings should be fixed,
> especially when it comes to sparse.
OK, I got it.
>
> The aim is not to get to zero warnings - it's to get to a point where
> the code is correct, and plastering the code with __force casts means
> it isn't correct - you're just masking the warning.
>
> So no, I really don't like this. And I really don't like seeing
> __force being used in open code in casts.
OK, I will clear only the first warning and leave the second warning.
>
--
Regards,
Zhen Lei
On 2022/10/11 10:13, Leizhen (ThunderTown) wrote:
>
>
> On 2022/10/11 0:05, Russell King (Oracle) wrote:
>> On Mon, Oct 10, 2022 at 05:53:45PM +0800, Zhen Lei wrote:
>>> Fix the following warnings:
>>> warning: incorrect type in initializer (different address spaces)
>>> expected unsigned short [noderef] __user *register __p
>>> got unsigned short [usertype] *
>>> warning: cast removes address space '__user' of expression
>>
>> I have a general principle that not all warnings should be fixed,
>> especially when it comes to sparse.
>
> OK, I got it.
>
>>
>> The aim is not to get to zero warnings - it's to get to a point where
>> the code is correct, and plastering the code with __force casts means
>> it isn't correct - you're just masking the warning.
>>
>> So no, I really don't like this. And I really don't like seeing
>> __force being used in open code in casts.
>
> OK, I will clear only the first warning and leave the second warning.
Sorry, Maybe I misunderstood. '__force casts' mentioned here may include
not only '(__force u16 *)', but also '(u16 __user *)'.
>
>>
>
--
Regards,
Zhen Lei
On Tue, Oct 11, 2022 at 10:29:58AM +0800, Leizhen (ThunderTown) wrote:
> On 2022/10/10 19:06, Ard Biesheuvel wrote:
> > On Mon, 10 Oct 2022 at 12:58, Leizhen (ThunderTown)
> > <[email protected]> wrote:
> >> On 2022/10/10 18:20, Ard Biesheuvel wrote:
> >>> On Mon, 10 Oct 2022 at 11:56, Zhen Lei <[email protected]> wrote:
> >>>>
> >>>> Fix the following warnings:
> >>>> warning: incorrect type in initializer (different address spaces)
> >>>> expected unsigned short [noderef] __user *register __p
> >>>> got unsigned short [usertype] *
> >>>> warning: cast removes address space '__user' of expression
> >>>>
> >>>> Signed-off-by: Zhen Lei <[email protected]>
> >>>> ---
> >>>> arch/arm/kernel/traps.c | 10 +++++-----
> >>>> 1 file changed, 5 insertions(+), 5 deletions(-)
> >>>>
> >>>> diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
> >>>> index 20b2db6dcd1ced7..34aa80c09c508c1 100644
> >>>> --- a/arch/arm/kernel/traps.c
> >>>> +++ b/arch/arm/kernel/traps.c
> >>>> @@ -188,9 +188,9 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
> >>>> }
> >>>> } else {
> >>>> if (thumb)
> >>>> - bad = get_user(val, &((u16 *)addr)[i]);
> >>>> + bad = get_user(val, &((u16 __user *)addr)[i]);
> >>>> else
> >>>> - bad = get_user(val, &((u32 *)addr)[i]);
> >>>> + bad = get_user(val, &((u32 __user *)addr)[i]);
> >>>> }
> >>>>
> >>>> if (!bad)
> >>>> @@ -455,15 +455,15 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
> >>>> if (processor_mode(regs) == SVC_MODE) {
> >>>> #ifdef CONFIG_THUMB2_KERNEL
> >>>> if (thumb_mode(regs)) {
> >>>> - instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
> >>>> + instr = __mem_to_opcode_thumb16(((__force u16 *)pc)[0]);
> >>>
> >>> Shouldn't this be __user as well? (and below)
> >>
> >> unsigned int instr;
> >> void __user *pc;
> >>
> >> The __user can clear the warning, but a new warning will be generated.
> >>
> >> instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
> >> ^new ^old
> >>
> >> arch/arm/kernel/traps.c:473:33: warning: dereference of noderef expression
> >>
> >
> > This is because dereferencing a __user pointer is not permitted.
> >
> > So this code should be using get_kernel_nofault() here not a plain
> > dereference of PC. So better to fix that properly instead of papering
> > over it with a __force cast just to make sparse happy.
>
> How about:
> @@ -451,9 +451,9 @@ int call_undef_hook(struct pt_regs *regs, unsigned int instr)
> asmlinkage void do_undefinstr(struct pt_regs *regs)
> {
> unsigned int instr;
> - void __user *pc;
> + void *pc;
>
> - pc = (void __user *)instruction_pointer(regs);
> + pc = (void *)instruction_pointer(regs);
>
> if (processor_mode(regs) == SVC_MODE) {
> #ifdef CONFIG_THUMB2_KERNEL
> @@ -497,7 +497,7 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
> }
> #endif
> arm_notify_die("Oops - undefined instruction", regs,
> - SIGILL, ILL_ILLOPC, pc, 0, 6);
> + SIGILL, ILL_ILLOPC, (void __user *)pc, 0, 6);
> }
> NOKPROBE_SYMBOL(do_undefinstr)
>
>
> The 'pc' may come from kernel or user. And I found that all the get_user()
> calls have already done type casts to the pc, except arm_notify_die().
> I think the above changes are reasonable.
If we're going to do that, lets do it properly - I think the above would
need some __force usage to stop sparse complaining, whereas I don't
think this will (untested):
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 3f468ac98592..827cbc022900 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -449,36 +449,45 @@ int call_undef_hook(struct pt_regs *regs, unsigned int instr)
asmlinkage void do_undefinstr(struct pt_regs *regs)
{
unsigned int instr;
- void __user *pc;
+ unsigned long pc;
- pc = (void __user *)instruction_pointer(regs);
+ pc = instruction_pointer(regs);
if (processor_mode(regs) == SVC_MODE) {
-#ifdef CONFIG_THUMB2_KERNEL
- if (thumb_mode(regs)) {
- instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
+ if (IS_ENABLED(CONFIG_THUMB2_KERNEL) && thumb_mode(regs)) {
+ u16 *tpc = (u16 *)pc;
+
+ instr = __mem_to_opcode_thumb16(tpc[0]);
if (is_wide_instruction(instr)) {
u16 inst2;
- inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
+
+ inst2 = __mem_to_opcode_thumb16(tpc[1]);
instr = __opcode_thumb32_compose(instr, inst2);
}
- } else
-#endif
- instr = __mem_to_opcode_arm(*(u32 *) pc);
+ } else {
+ u32 *apc = (u32 *)pc;
+
+ instr = __mem_to_opcode_arm(*apc);
+ }
} else if (thumb_mode(regs)) {
- if (get_user(instr, (u16 __user *)pc))
+ u16 __user *tpc = (u16 __user *)pc;
+
+ if (get_user(instr, tpc))
goto die_sig;
instr = __mem_to_opcode_thumb16(instr);
if (is_wide_instruction(instr)) {
unsigned int instr2;
- if (get_user(instr2, (u16 __user *)pc+1))
+ if (get_user(instr2, tpc + 1))
goto die_sig;
instr2 = __mem_to_opcode_thumb16(instr2);
instr = __opcode_thumb32_compose(instr, instr2);
}
} else {
- if (get_user(instr, (u32 __user *)pc))
+ u32 __user *apc = (u32 __user *)pc;
+
+ if (get_user(instr, apc))
goto die_sig;
+
instr = __mem_to_opcode_arm(instr);
}
@@ -495,7 +504,7 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
}
#endif
arm_notify_die("Oops - undefined instruction", regs,
- SIGILL, ILL_ILLOPC, pc, 0, 6);
+ SIGILL, ILL_ILLOPC, (void __user *)pc, 0, 6);
}
NOKPROBE_SYMBOL(do_undefinstr)
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
On 2022/10/13 18:51, Russell King (Oracle) wrote:
> On Tue, Oct 11, 2022 at 10:29:58AM +0800, Leizhen (ThunderTown) wrote:
>> On 2022/10/10 19:06, Ard Biesheuvel wrote:
>>> On Mon, 10 Oct 2022 at 12:58, Leizhen (ThunderTown)
>>> <[email protected]> wrote:
>>>> On 2022/10/10 18:20, Ard Biesheuvel wrote:
>>>>> On Mon, 10 Oct 2022 at 11:56, Zhen Lei <[email protected]> wrote:
>>>>>>
>>>>>> Fix the following warnings:
>>>>>> warning: incorrect type in initializer (different address spaces)
>>>>>> expected unsigned short [noderef] __user *register __p
>>>>>> got unsigned short [usertype] *
>>>>>> warning: cast removes address space '__user' of expression
>>>>>>
>>>>>> Signed-off-by: Zhen Lei <[email protected]>
>>>>>> ---
>>>>>> arch/arm/kernel/traps.c | 10 +++++-----
>>>>>> 1 file changed, 5 insertions(+), 5 deletions(-)
>>>>>>
>>>>>> diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
>>>>>> index 20b2db6dcd1ced7..34aa80c09c508c1 100644
>>>>>> --- a/arch/arm/kernel/traps.c
>>>>>> +++ b/arch/arm/kernel/traps.c
>>>>>> @@ -188,9 +188,9 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
>>>>>> }
>>>>>> } else {
>>>>>> if (thumb)
>>>>>> - bad = get_user(val, &((u16 *)addr)[i]);
>>>>>> + bad = get_user(val, &((u16 __user *)addr)[i]);
>>>>>> else
>>>>>> - bad = get_user(val, &((u32 *)addr)[i]);
>>>>>> + bad = get_user(val, &((u32 __user *)addr)[i]);
>>>>>> }
>>>>>>
>>>>>> if (!bad)
>>>>>> @@ -455,15 +455,15 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
>>>>>> if (processor_mode(regs) == SVC_MODE) {
>>>>>> #ifdef CONFIG_THUMB2_KERNEL
>>>>>> if (thumb_mode(regs)) {
>>>>>> - instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
>>>>>> + instr = __mem_to_opcode_thumb16(((__force u16 *)pc)[0]);
>>>>>
>>>>> Shouldn't this be __user as well? (and below)
>>>>
>>>> unsigned int instr;
>>>> void __user *pc;
>>>>
>>>> The __user can clear the warning, but a new warning will be generated.
>>>>
>>>> instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
>>>> ^new ^old
>>>>
>>>> arch/arm/kernel/traps.c:473:33: warning: dereference of noderef expression
>>>>
>>>
>>> This is because dereferencing a __user pointer is not permitted.
>>>
>>> So this code should be using get_kernel_nofault() here not a plain
>>> dereference of PC. So better to fix that properly instead of papering
>>> over it with a __force cast just to make sparse happy.
>>
>> How about:
>> @@ -451,9 +451,9 @@ int call_undef_hook(struct pt_regs *regs, unsigned int instr)
>> asmlinkage void do_undefinstr(struct pt_regs *regs)
>> {
>> unsigned int instr;
>> - void __user *pc;
>> + void *pc;
>>
>> - pc = (void __user *)instruction_pointer(regs);
>> + pc = (void *)instruction_pointer(regs);
>>
>> if (processor_mode(regs) == SVC_MODE) {
>> #ifdef CONFIG_THUMB2_KERNEL
>> @@ -497,7 +497,7 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
>> }
>> #endif
>> arm_notify_die("Oops - undefined instruction", regs,
>> - SIGILL, ILL_ILLOPC, pc, 0, 6);
>> + SIGILL, ILL_ILLOPC, (void __user *)pc, 0, 6);
>> }
>> NOKPROBE_SYMBOL(do_undefinstr)
>>
>>
>> The 'pc' may come from kernel or user. And I found that all the get_user()
>> calls have already done type casts to the pc, except arm_notify_die().
>> I think the above changes are reasonable.
>
> If we're going to do that, lets do it properly - I think the above would
> need some __force usage to stop sparse complaining, whereas I don't
No need to add __force. I sent it after testing.
$ cat .config | grep THUMB2
CONFIG_THUMB2_KERNEL=y
$ make C=2 ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- arch/arm/kernel/traps.o
CHECK scripts/mod/empty.c
CALL scripts/checksyscalls.sh
CHECK arch/arm/kernel/traps.c
arch/arm/kernel/traps.c:97:6: warning: symbol 'dump_backtrace_stm' was not declared. Should it be static?
arch/arm/kernel/traps.c:451:17: warning: symbol 'do_undefinstr' was not declared. Should it be static?
arch/arm/kernel/traps.c:516:39: warning: symbol 'handle_fiq_as_nmi' was not declared. Should it be static?
arch/arm/kernel/traps.c:535:17: warning: symbol 'bad_mode' was not declared. Should it be static?
arch/arm/kernel/traps.c:608:16: warning: symbol 'arm_syscall' was not declared. Should it be static?
arch/arm/kernel/traps.c:734:1: warning: symbol 'baddataabort' was not declared. Should it be static?
arch/arm/kernel/traps.c:774:17: warning: symbol '__div0' was not declared. Should it be static?
arch/arm/kernel/traps.c:781:6: warning: symbol 'abort' was not declared. Should it be static?
arch/arm/kernel/traps.c:905:12: warning: symbol 'overflow_stack_ptr' was not declared. Should it be static?
arch/arm/kernel/traps.c:922:17: warning: symbol 'handle_bad_stack' was not declared. Should it be static?
> think this will (untested):
>
> diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
> index 3f468ac98592..827cbc022900 100644
> --- a/arch/arm/kernel/traps.c
> +++ b/arch/arm/kernel/traps.c
> @@ -449,36 +449,45 @@ int call_undef_hook(struct pt_regs *regs, unsigned int instr)
> asmlinkage void do_undefinstr(struct pt_regs *regs)
> {
> unsigned int instr;
> - void __user *pc;
> + unsigned long pc;
>
> - pc = (void __user *)instruction_pointer(regs);
> + pc = instruction_pointer(regs);
>
> if (processor_mode(regs) == SVC_MODE) {
> -#ifdef CONFIG_THUMB2_KERNEL
> - if (thumb_mode(regs)) {
> - instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
> + if (IS_ENABLED(CONFIG_THUMB2_KERNEL) && thumb_mode(regs)) {
> + u16 *tpc = (u16 *)pc;
> +
> + instr = __mem_to_opcode_thumb16(tpc[0]);
> if (is_wide_instruction(instr)) {
> u16 inst2;
> - inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
> +
> + inst2 = __mem_to_opcode_thumb16(tpc[1]);
> instr = __opcode_thumb32_compose(instr, inst2);
> }
> - } else
> -#endif
> - instr = __mem_to_opcode_arm(*(u32 *) pc);
> + } else {
> + u32 *apc = (u32 *)pc;
> +
> + instr = __mem_to_opcode_arm(*apc);
> + }
> } else if (thumb_mode(regs)) {
> - if (get_user(instr, (u16 __user *)pc))
> + u16 __user *tpc = (u16 __user *)pc;
> +
> + if (get_user(instr, tpc))
> goto die_sig;
> instr = __mem_to_opcode_thumb16(instr);
> if (is_wide_instruction(instr)) {
> unsigned int instr2;
> - if (get_user(instr2, (u16 __user *)pc+1))
> + if (get_user(instr2, tpc + 1))
> goto die_sig;
> instr2 = __mem_to_opcode_thumb16(instr2);
> instr = __opcode_thumb32_compose(instr, instr2);
> }
> } else {
> - if (get_user(instr, (u32 __user *)pc))
> + u32 __user *apc = (u32 __user *)pc;
> +
> + if (get_user(instr, apc))
> goto die_sig;
> +
> instr = __mem_to_opcode_arm(instr);
> }
>
> @@ -495,7 +504,7 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
> }
> #endif
> arm_notify_die("Oops - undefined instruction", regs,
> - SIGILL, ILL_ILLOPC, pc, 0, 6);
> + SIGILL, ILL_ILLOPC, (void __user *)pc, 0, 6);
> }
> NOKPROBE_SYMBOL(do_undefinstr)
>
>
--
Regards,
Zhen Lei
On 2022/10/13 18:51, Russell King (Oracle) wrote:
> On Tue, Oct 11, 2022 at 10:29:58AM +0800, Leizhen (ThunderTown) wrote:
>> On 2022/10/10 19:06, Ard Biesheuvel wrote:
>>> On Mon, 10 Oct 2022 at 12:58, Leizhen (ThunderTown)
>>> <[email protected]> wrote:
>>>> On 2022/10/10 18:20, Ard Biesheuvel wrote:
>>>>> On Mon, 10 Oct 2022 at 11:56, Zhen Lei <[email protected]> wrote:
>>>>>>
>>>>>> Fix the following warnings:
>>>>>> warning: incorrect type in initializer (different address spaces)
>>>>>> expected unsigned short [noderef] __user *register __p
>>>>>> got unsigned short [usertype] *
>>>>>> warning: cast removes address space '__user' of expression
>>>>>>
>>>>>> Signed-off-by: Zhen Lei <[email protected]>
>>>>>> ---
>>>>>> arch/arm/kernel/traps.c | 10 +++++-----
>>>>>> 1 file changed, 5 insertions(+), 5 deletions(-)
>>>>>>
>>>>>> diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
>>>>>> index 20b2db6dcd1ced7..34aa80c09c508c1 100644
>>>>>> --- a/arch/arm/kernel/traps.c
>>>>>> +++ b/arch/arm/kernel/traps.c
>>>>>> @@ -188,9 +188,9 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
>>>>>> }
>>>>>> } else {
>>>>>> if (thumb)
>>>>>> - bad = get_user(val, &((u16 *)addr)[i]);
>>>>>> + bad = get_user(val, &((u16 __user *)addr)[i]);
>>>>>> else
>>>>>> - bad = get_user(val, &((u32 *)addr)[i]);
>>>>>> + bad = get_user(val, &((u32 __user *)addr)[i]);
>>>>>> }
>>>>>>
>>>>>> if (!bad)
>>>>>> @@ -455,15 +455,15 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
>>>>>> if (processor_mode(regs) == SVC_MODE) {
>>>>>> #ifdef CONFIG_THUMB2_KERNEL
>>>>>> if (thumb_mode(regs)) {
>>>>>> - instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
>>>>>> + instr = __mem_to_opcode_thumb16(((__force u16 *)pc)[0]);
>>>>>
>>>>> Shouldn't this be __user as well? (and below)
>>>>
>>>> unsigned int instr;
>>>> void __user *pc;
>>>>
>>>> The __user can clear the warning, but a new warning will be generated.
>>>>
>>>> instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
>>>> ^new ^old
>>>>
>>>> arch/arm/kernel/traps.c:473:33: warning: dereference of noderef expression
>>>>
>>>
>>> This is because dereferencing a __user pointer is not permitted.
>>>
>>> So this code should be using get_kernel_nofault() here not a plain
>>> dereference of PC. So better to fix that properly instead of papering
>>> over it with a __force cast just to make sparse happy.
>>
>> How about:
>> @@ -451,9 +451,9 @@ int call_undef_hook(struct pt_regs *regs, unsigned int instr)
>> asmlinkage void do_undefinstr(struct pt_regs *regs)
>> {
>> unsigned int instr;
>> - void __user *pc;
>> + void *pc;
>>
>> - pc = (void __user *)instruction_pointer(regs);
>> + pc = (void *)instruction_pointer(regs);
>>
>> if (processor_mode(regs) == SVC_MODE) {
>> #ifdef CONFIG_THUMB2_KERNEL
>> @@ -497,7 +497,7 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
>> }
>> #endif
>> arm_notify_die("Oops - undefined instruction", regs,
>> - SIGILL, ILL_ILLOPC, pc, 0, 6);
>> + SIGILL, ILL_ILLOPC, (void __user *)pc, 0, 6);
>> }
>> NOKPROBE_SYMBOL(do_undefinstr)
>>
>>
>> The 'pc' may come from kernel or user. And I found that all the get_user()
>> calls have already done type casts to the pc, except arm_notify_die().
>> I think the above changes are reasonable.
>
> If we're going to do that, lets do it properly - I think the above would
> need some __force usage to stop sparse complaining, whereas I don't
> think this will (untested):
The following changes are a little too big, and the above changes have solved
the problem completely. In order to focus on the main target, I removed this
part of the modification in v4. I hope you'll take the time to review v4.
>
> diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
> index 3f468ac98592..827cbc022900 100644
> --- a/arch/arm/kernel/traps.c
> +++ b/arch/arm/kernel/traps.c
> @@ -449,36 +449,45 @@ int call_undef_hook(struct pt_regs *regs, unsigned int instr)
> asmlinkage void do_undefinstr(struct pt_regs *regs)
> {
> unsigned int instr;
> - void __user *pc;
> + unsigned long pc;
The following changes need to be added:
@@ -487,7 +497,7 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
die_sig:
#ifdef CONFIG_DEBUG_USER
if (user_debug & UDBG_UNDEFINED) {
- pr_info("%s (%d): undefined instruction: pc=%px\n",
+ pr_info("%s (%d): undefined instruction: pc=%lx\n",
current->comm, task_pid_nr(current), pc);
__show_regs(regs);
dump_instr(KERN_INFO, regs);
>
> - pc = (void __user *)instruction_pointer(regs);
> + pc = instruction_pointer(regs);
>
> if (processor_mode(regs) == SVC_MODE) {
> -#ifdef CONFIG_THUMB2_KERNEL
> - if (thumb_mode(regs)) {
> - instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
> + if (IS_ENABLED(CONFIG_THUMB2_KERNEL) && thumb_mode(regs)) {
> + u16 *tpc = (u16 *)pc;
> +
> + instr = __mem_to_opcode_thumb16(tpc[0]);
> if (is_wide_instruction(instr)) {
> u16 inst2;
> - inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
> +
> + inst2 = __mem_to_opcode_thumb16(tpc[1]);
> instr = __opcode_thumb32_compose(instr, inst2);
> }
> - } else
> -#endif
> - instr = __mem_to_opcode_arm(*(u32 *) pc);
> + } else {
> + u32 *apc = (u32 *)pc;
> +
> + instr = __mem_to_opcode_arm(*apc);
> + }
> } else if (thumb_mode(regs)) {
> - if (get_user(instr, (u16 __user *)pc))
> + u16 __user *tpc = (u16 __user *)pc;
> +
> + if (get_user(instr, tpc))
> goto die_sig;
> instr = __mem_to_opcode_thumb16(instr);
> if (is_wide_instruction(instr)) {
> unsigned int instr2;
> - if (get_user(instr2, (u16 __user *)pc+1))
> + if (get_user(instr2, tpc + 1))
> goto die_sig;
> instr2 = __mem_to_opcode_thumb16(instr2);
> instr = __opcode_thumb32_compose(instr, instr2);
> }
> } else {
> - if (get_user(instr, (u32 __user *)pc))
> + u32 __user *apc = (u32 __user *)pc;
> +
> + if (get_user(instr, apc))
> goto die_sig;
> +
> instr = __mem_to_opcode_arm(instr);
> }
>
> @@ -495,7 +504,7 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
> }
> #endif
> arm_notify_die("Oops - undefined instruction", regs,
> - SIGILL, ILL_ILLOPC, pc, 0, 6);
> + SIGILL, ILL_ILLOPC, (void __user *)pc, 0, 6);
> }
> NOKPROBE_SYMBOL(do_undefinstr)
>
>
--
Regards,
Zhen Lei