Hi,
this can be triggered simply by running
# echo 0 > /sys/devices/system/cpu/cpu3/online
# echo 1 > /sys/devices/system/cpu/cpu3/online
[ 455.904854] ==================================================================
[ 455.906108] BUG: KASAN: global-out-of-bounds in unmap_kernel_at_el0+0x70/0x1a0
[ 455.906668] Read of size 4 at addr ffff200008e3a9d8 by task swapper/3/0
[ 455.907122]
[ 455.907647] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 4.17.0-rc1-00257-gbf20b92a3b12 #76
[ 455.908158] Hardware name: linux,dummy-virt (DT)
[ 455.908802] Call trace:
[ 455.909126] dump_backtrace+0x0/0x230
[ 455.909522] show_stack+0x14/0x20
[ 455.909848] dump_stack+0xa8/0xcc
[ 455.910180] print_address_description+0x13c/0x250
[ 455.910576] kasan_report+0x254/0x328
[ 455.910985] __asan_load4+0x88/0xb0
[ 455.911326] unmap_kernel_at_el0+0x70/0x1a0
[ 455.911702] __verify_local_cpu_caps+0x78/0x178
[ 455.912098] verify_local_cpu_caps+0x4c/0x60
[ 455.912509] check_local_cpu_capabilities+0x64/0x158
[ 455.912955] secondary_start_kernel+0x178/0x260
[ 455.913366]
[ 455.913586] The buggy address belongs to the variable:
[ 455.914026] kpti_safe_list.26846+0x18/0x1460
[ 455.914382]
[ 455.914606] Memory state around the buggy address:
[ 455.915349] ffff200008e3a880: 00 00 00 01 fa fa fa fa 00 00 04 fa fa fa fa fa
[ 455.915942] ffff200008e3a900: 03 fa fa fa fa fa fa fa 04 fa fa fa fa fa fa fa
[ 455.916483] >ffff200008e3a980: 00 00 00 06 fa fa fa fa 00 00 00 fa fa fa fa fa
[ 455.917077] ^
[ 455.917539] ffff200008e3aa00: 00 00 00 00 00 00 00 05 fa fa fa fa 00 00 00 00
[ 455.918055] ffff200008e3aa80: 00 00 00 00 03 fa fa fa fa fa fa fa 00 00 00 00
[ 455.918579] ==================================================================
Issue is new with 4.17-rc. Can provide .config if needed. Device was
qemu-system-aarch64.
Jan
On Sun, Apr 22, 2018 at 12:47:57PM +0200, Jan Kiszka wrote:
> Hi,
>
> this can be triggered simply by running
>
> # echo 0 > /sys/devices/system/cpu/cpu3/online
> # echo 1 > /sys/devices/system/cpu/cpu3/online
>
> [ 455.904854] ==================================================================
> [ 455.906108] BUG: KASAN: global-out-of-bounds in unmap_kernel_at_el0+0x70/0x1a0
> [ 455.906668] Read of size 4 at addr ffff200008e3a9d8 by task swapper/3/0
It looks like we miss a sentinel in kpti_safe_list.
Does the below help?
Mark.
---->8----
From ade322407e3d6d1f50e558ebd50d2c1c7bd811c2 Mon Sep 17 00:00:00 2001
From: Mark Rutland <[email protected]>
Date: Sun, 22 Apr 2018 19:58:08 +0100
Subject: [PATCH] arm64: add sentinel to kpti_safe_list
We're missing a sentinel entry in kpti_safe_list. Thus is_midr_in_range_list()
can walk past the end of kpti_safe_list. Depending on the contents of memory,
this could erroneously match a CPU's MIDR, cause a data abort, or other bad
outcomes.
Add the sentinel entry to avoid this.
Fixes: be5b299830c63ed7 ("arm64: capabilities: Add support for checks based on a list of MIDRs")
Signed-off-by: Mark Rutland <[email protected]>
Reported-by: Jan Kiszka <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Suzuki K Poulose <[email protected]>
Cc: Will Deacon <[email protected]>
---
arch/arm64/kernel/cpufeature.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 536d572e5596..9d1b06d67c53 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -868,6 +868,7 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
static const struct midr_range kpti_safe_list[] = {
MIDR_ALL_VERSIONS(MIDR_CAVIUM_THUNDERX2),
MIDR_ALL_VERSIONS(MIDR_BRCM_VULCAN),
+ { /* sentinel */ }
};
char const *str = "command line option";
--
2.11.0
On 2018-04-22 21:06, Mark Rutland wrote:
> On Sun, Apr 22, 2018 at 12:47:57PM +0200, Jan Kiszka wrote:
>> Hi,
>>
>> this can be triggered simply by running
>>
>> # echo 0 > /sys/devices/system/cpu/cpu3/online
>> # echo 1 > /sys/devices/system/cpu/cpu3/online
>>
>> [ 455.904854] ==================================================================
>> [ 455.906108] BUG: KASAN: global-out-of-bounds in unmap_kernel_at_el0+0x70/0x1a0
>> [ 455.906668] Read of size 4 at addr ffff200008e3a9d8 by task swapper/3/0
>
> It looks like we miss a sentinel in kpti_safe_list.
>
> Does the below help?
>
> Mark.
>
> ---->8----
> From ade322407e3d6d1f50e558ebd50d2c1c7bd811c2 Mon Sep 17 00:00:00 2001
> From: Mark Rutland <[email protected]>
> Date: Sun, 22 Apr 2018 19:58:08 +0100
> Subject: [PATCH] arm64: add sentinel to kpti_safe_list
>
> We're missing a sentinel entry in kpti_safe_list. Thus is_midr_in_range_list()
> can walk past the end of kpti_safe_list. Depending on the contents of memory,
> this could erroneously match a CPU's MIDR, cause a data abort, or other bad
> outcomes.
>
> Add the sentinel entry to avoid this.
>
> Fixes: be5b299830c63ed7 ("arm64: capabilities: Add support for checks based on a list of MIDRs")
> Signed-off-by: Mark Rutland <[email protected]>
> Reported-by: Jan Kiszka <[email protected]>
> Cc: Catalin Marinas <[email protected]>
> Cc: Suzuki K Poulose <[email protected]>
> Cc: Will Deacon <[email protected]>
> ---
> arch/arm64/kernel/cpufeature.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 536d572e5596..9d1b06d67c53 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -868,6 +868,7 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
> static const struct midr_range kpti_safe_list[] = {
> MIDR_ALL_VERSIONS(MIDR_CAVIUM_THUNDERX2),
> MIDR_ALL_VERSIONS(MIDR_BRCM_VULCAN),
> + { /* sentinel */ }
> };
> char const *str = "command line option";
>
>
Jep, all fine now!
Jan
On Mon, Apr 23, 2018 at 07:00:52AM +0200, Jan Kiszka wrote:
> On 2018-04-22 21:06, Mark Rutland wrote:
> > Does the below help?
> > From ade322407e3d6d1f50e558ebd50d2c1c7bd811c2 Mon Sep 17 00:00:00 2001
> > From: Mark Rutland <[email protected]>
> > Date: Sun, 22 Apr 2018 19:58:08 +0100
> > Subject: [PATCH] arm64: add sentinel to kpti_safe_list
> >
> > We're missing a sentinel entry in kpti_safe_list. Thus is_midr_in_range_list()
> > can walk past the end of kpti_safe_list. Depending on the contents of memory,
> > this could erroneously match a CPU's MIDR, cause a data abort, or other bad
> > outcomes.
> >
> > Add the sentinel entry to avoid this.
> >
> > Fixes: be5b299830c63ed7 ("arm64: capabilities: Add support for checks based on a list of MIDRs")
> > Signed-off-by: Mark Rutland <[email protected]>
> > Reported-by: Jan Kiszka <[email protected]>
> > Cc: Catalin Marinas <[email protected]>
> > Cc: Suzuki K Poulose <[email protected]>
> > Cc: Will Deacon <[email protected]>
> > ---
> > arch/arm64/kernel/cpufeature.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> > index 536d572e5596..9d1b06d67c53 100644
> > --- a/arch/arm64/kernel/cpufeature.c
> > +++ b/arch/arm64/kernel/cpufeature.c
> > @@ -868,6 +868,7 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
> > static const struct midr_range kpti_safe_list[] = {
> > MIDR_ALL_VERSIONS(MIDR_CAVIUM_THUNDERX2),
> > MIDR_ALL_VERSIONS(MIDR_BRCM_VULCAN),
> > + { /* sentinel */ }
> > };
> > char const *str = "command line option";
> >
> >
>
> Jep, all fine now!
Cool. Can I take that as a Tested-by?
Mark.
On 2018-04-23 12:29, Mark Rutland wrote:
> On Mon, Apr 23, 2018 at 07:00:52AM +0200, Jan Kiszka wrote:
>> On 2018-04-22 21:06, Mark Rutland wrote:
>
>>> Does the below help?
>
>>> From ade322407e3d6d1f50e558ebd50d2c1c7bd811c2 Mon Sep 17 00:00:00 2001
>>> From: Mark Rutland <[email protected]>
>>> Date: Sun, 22 Apr 2018 19:58:08 +0100
>>> Subject: [PATCH] arm64: add sentinel to kpti_safe_list
>>>
>>> We're missing a sentinel entry in kpti_safe_list. Thus is_midr_in_range_list()
>>> can walk past the end of kpti_safe_list. Depending on the contents of memory,
>>> this could erroneously match a CPU's MIDR, cause a data abort, or other bad
>>> outcomes.
>>>
>>> Add the sentinel entry to avoid this.
>>>
>>> Fixes: be5b299830c63ed7 ("arm64: capabilities: Add support for checks based on a list of MIDRs")
>>> Signed-off-by: Mark Rutland <[email protected]>
>>> Reported-by: Jan Kiszka <[email protected]>
>>> Cc: Catalin Marinas <[email protected]>
>>> Cc: Suzuki K Poulose <[email protected]>
>>> Cc: Will Deacon <[email protected]>
>>> ---
>>> arch/arm64/kernel/cpufeature.c | 1 +
>>> 1 file changed, 1 insertion(+)
>>>
>>> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
>>> index 536d572e5596..9d1b06d67c53 100644
>>> --- a/arch/arm64/kernel/cpufeature.c
>>> +++ b/arch/arm64/kernel/cpufeature.c
>>> @@ -868,6 +868,7 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
>>> static const struct midr_range kpti_safe_list[] = {
>>> MIDR_ALL_VERSIONS(MIDR_CAVIUM_THUNDERX2),
>>> MIDR_ALL_VERSIONS(MIDR_BRCM_VULCAN),
>>> + { /* sentinel */ }
>>> };
>>> char const *str = "command line option";
>>>
>>>
>>
>> Jep, all fine now!
>
> Cool. Can I take that as a Tested-by?
Yes, sorry:
Tested-by: Jan Kiszka <[email protected]>
Jan
On Mon, Apr 23, 2018 at 12:33:17PM +0200, Jan Kiszka wrote:
> On 2018-04-23 12:29, Mark Rutland wrote:
> > On Mon, Apr 23, 2018 at 07:00:52AM +0200, Jan Kiszka wrote:
> >> On 2018-04-22 21:06, Mark Rutland wrote:
> >
> >>> Does the below help?
[...]
> >> Jep, all fine now!
> >
> > Cool. Can I take that as a Tested-by?
>
> Yes, sorry:
>
> Tested-by: Jan Kiszka <[email protected]>
>
> Jan
Cheers!
I'll fix up the reported-by address likewise, and send this out as a
patch.
Thanks,
Mark.