2018-04-24 14:19:34

by Christophe Leroy

Subject: [PATCH] powerpc/signal32: Use fault_in_pages_readable() to prefault user context

Use fault_in_pages_readable() to prefault user context
instead of open coding

Signed-off-by: Christophe Leroy <[email protected]>
---
arch/powerpc/kernel/signal_32.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index 492f03451877..cfacb2726152 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -25,6 +25,7 @@
#include <linux/errno.h>
#include <linux/elf.h>
#include <linux/ptrace.h>
+#include <linux/pagemap.h>
#include <linux/ratelimit.h>
#ifdef CONFIG_PPC64
#include <linux/syscalls.h>
@@ -1045,7 +1046,6 @@ long sys_swapcontext(struct ucontext __user *old_ctx,
struct ucontext __user *new_ctx,
int ctx_size, int r6, int r7, int r8, struct pt_regs *regs)
{
- unsigned char tmp __maybe_unused;
int ctx_has_vsx_region = 0;

#ifdef CONFIG_PPC64
@@ -1109,9 +1109,8 @@ long sys_swapcontext(struct ucontext __user *old_ctx,
}
if (new_ctx == NULL)
return 0;
- if (!access_ok(VERIFY_READ, new_ctx, ctx_size)
- || __get_user(tmp, (u8 __user *) new_ctx)
- || __get_user(tmp, (u8 __user *) new_ctx + ctx_size - 1))
+ if (!access_ok(VERIFY_READ, new_ctx, ctx_size) ||
+ fault_in_pages_readable((u8 __user *)new_ctx, ctx_size))
return -EFAULT;

/*
@@ -1231,7 +1230,6 @@ int sys_debug_setcontext(struct ucontext __user *ctx,
{
struct sig_dbg_op op;
int i;
- unsigned char tmp __maybe_unused;
unsigned long new_msr = regs->msr;
#ifdef CONFIG_PPC_ADV_DEBUG_REGS
unsigned long new_dbcr0 = current->thread.debug.dbcr0;
@@ -1287,9 +1285,8 @@ int sys_debug_setcontext(struct ucontext __user *ctx,
current->thread.debug.dbcr0 = new_dbcr0;
#endif

- if (!access_ok(VERIFY_READ, ctx, sizeof(*ctx))
- || __get_user(tmp, (u8 __user *) ctx)
- || __get_user(tmp, (u8 __user *) (ctx + 1) - 1))
+ if (!access_ok(VERIFY_READ, ctx, sizeof(*ctx)) ||
+ fault_in_pages_readable((u8 __user *)ctx, 1))
return -EFAULT;

/*
--
2.13.3

2018-04-24 14:47:39

by Mathieu Malaterre

Subject: Re: [PATCH] powerpc/signal32: Use fault_in_pages_readable() to prefault user context

On Tue, Apr 24, 2018 at 4:17 PM, Christophe Leroy
<[email protected]> wrote:
> Use fault_in_pages_readable() to prefault user context
> instead of open coding
>
> Signed-off-by: Christophe Leroy <[email protected]>
> ---
> arch/powerpc/kernel/signal_32.c | 13 +++++--------
> 1 file changed, 5 insertions(+), 8 deletions(-)
>
> diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
> index 492f03451877..cfacb2726152 100644
> --- a/arch/powerpc/kernel/signal_32.c
> +++ b/arch/powerpc/kernel/signal_32.c
> @@ -25,6 +25,7 @@
> #include <linux/errno.h>
> #include <linux/elf.h>
> #include <linux/ptrace.h>
> +#include <linux/pagemap.h>
> #include <linux/ratelimit.h>
> #ifdef CONFIG_PPC64
> #include <linux/syscalls.h>
> @@ -1045,7 +1046,6 @@ long sys_swapcontext(struct ucontext __user *old_ctx,
> struct ucontext __user *new_ctx,
> int ctx_size, int r6, int r7, int r8, struct pt_regs *regs)
> {
> - unsigned char tmp __maybe_unused;
> int ctx_has_vsx_region = 0;
>
> #ifdef CONFIG_PPC64
> @@ -1109,9 +1109,8 @@ long sys_swapcontext(struct ucontext __user *old_ctx,
> }
> if (new_ctx == NULL)
> return 0;
> - if (!access_ok(VERIFY_READ, new_ctx, ctx_size)
> - || __get_user(tmp, (u8 __user *) new_ctx)
> - || __get_user(tmp, (u8 __user *) new_ctx + ctx_size - 1))
> + if (!access_ok(VERIFY_READ, new_ctx, ctx_size) ||
> + fault_in_pages_readable((u8 __user *)new_ctx, ctx_size))
> return -EFAULT;
>
> /*
> @@ -1231,7 +1230,6 @@ int sys_debug_setcontext(struct ucontext __user *ctx,
> {
> struct sig_dbg_op op;
> int i;
> - unsigned char tmp __maybe_unused;
> unsigned long new_msr = regs->msr;
> #ifdef CONFIG_PPC_ADV_DEBUG_REGS
> unsigned long new_dbcr0 = current->thread.debug.dbcr0;
> @@ -1287,9 +1285,8 @@ int sys_debug_setcontext(struct ucontext __user *ctx,
> current->thread.debug.dbcr0 = new_dbcr0;
> #endif
>
> - if (!access_ok(VERIFY_READ, ctx, sizeof(*ctx))
> - || __get_user(tmp, (u8 __user *) ctx)
> - || __get_user(tmp, (u8 __user *) (ctx + 1) - 1))
> + if (!access_ok(VERIFY_READ, ctx, sizeof(*ctx)) ||
> + fault_in_pages_readable((u8 __user *)ctx, 1))

I believe you meant:

fault_in_pages_readable((u8 __user *)new_ctx, ctx_size)

Since (u8 __user *) (ctx + 1) - 1 really is (u8 __user *) new_ctx + ctx_size - 1

> return -EFAULT;
>
> /*
> --
> 2.13.3
>

2018-04-24 14:52:44

by Mathieu Malaterre

Subject: Re: [PATCH] powerpc/signal32: Use fault_in_pages_readable() to prefault user context

On Tue, Apr 24, 2018 at 4:45 PM, Mathieu Malaterre <[email protected]> wrote:
> On Tue, Apr 24, 2018 at 4:17 PM, Christophe Leroy
> <[email protected]> wrote:
>> Use fault_in_pages_readable() to prefault user context
>> instead of open coding
>>
>> Signed-off-by: Christophe Leroy <[email protected]>
>> ---
>> arch/powerpc/kernel/signal_32.c | 13 +++++--------
>> 1 file changed, 5 insertions(+), 8 deletions(-)
>>
>> diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
>> index 492f03451877..cfacb2726152 100644
>> --- a/arch/powerpc/kernel/signal_32.c
>> +++ b/arch/powerpc/kernel/signal_32.c
>> @@ -25,6 +25,7 @@
>> #include <linux/errno.h>
>> #include <linux/elf.h>
>> #include <linux/ptrace.h>
>> +#include <linux/pagemap.h>
>> #include <linux/ratelimit.h>
>> #ifdef CONFIG_PPC64
>> #include <linux/syscalls.h>
>> @@ -1045,7 +1046,6 @@ long sys_swapcontext(struct ucontext __user *old_ctx,
>> struct ucontext __user *new_ctx,
>> int ctx_size, int r6, int r7, int r8, struct pt_regs *regs)
>> {
>> - unsigned char tmp __maybe_unused;
>> int ctx_has_vsx_region = 0;
>>
>> #ifdef CONFIG_PPC64
>> @@ -1109,9 +1109,8 @@ long sys_swapcontext(struct ucontext __user *old_ctx,
>> }
>> if (new_ctx == NULL)
>> return 0;
>> - if (!access_ok(VERIFY_READ, new_ctx, ctx_size)
>> - || __get_user(tmp, (u8 __user *) new_ctx)
>> - || __get_user(tmp, (u8 __user *) new_ctx + ctx_size - 1))
>> + if (!access_ok(VERIFY_READ, new_ctx, ctx_size) ||
>> + fault_in_pages_readable((u8 __user *)new_ctx, ctx_size))
>> return -EFAULT;
>>
>> /*
>> @@ -1231,7 +1230,6 @@ int sys_debug_setcontext(struct ucontext __user *ctx,
>> {
>> struct sig_dbg_op op;
>> int i;
>> - unsigned char tmp __maybe_unused;
>> unsigned long new_msr = regs->msr;
>> #ifdef CONFIG_PPC_ADV_DEBUG_REGS
>> unsigned long new_dbcr0 = current->thread.debug.dbcr0;
>> @@ -1287,9 +1285,8 @@ int sys_debug_setcontext(struct ucontext __user *ctx,
>> current->thread.debug.dbcr0 = new_dbcr0;
>> #endif
>>
>> - if (!access_ok(VERIFY_READ, ctx, sizeof(*ctx))
>> - || __get_user(tmp, (u8 __user *) ctx)
>> - || __get_user(tmp, (u8 __user *) (ctx + 1) - 1))
>> + if (!access_ok(VERIFY_READ, ctx, sizeof(*ctx)) ||
>> + fault_in_pages_readable((u8 __user *)ctx, 1))
>
> I believe you meant:
>
> fault_in_pages_readable((u8 __user *)new_ctx, ctx_size)
>
> Since (u8 __user *) (ctx + 1) - 1 really is (u8 __user *) new_ctx + ctx_size - 1

Without the copy/paste errors:

[...]
fault_in_pages_readable((u8 __user *)ctx, sizeof(*ctx))

Since (u8 __user *) (ctx + 1) - 1 really is (u8 __user *) ctx + sizeof(*ctx) - 1
[...]
>> return -EFAULT;
>>
>> /*
>> --
>> 2.13.3
>>

2018-04-24 16:07:16

by Christophe Leroy

Subject: Re: [PATCH] powerpc/signal32: Use fault_in_pages_readable() to prefault user context

Le 24/04/2018 à 16:50, Mathieu Malaterre a écrit :
> On Tue, Apr 24, 2018 at 4:45 PM, Mathieu Malaterre <[email protected]> wrote:
>> On Tue, Apr 24, 2018 at 4:17 PM, Christophe Leroy
>> <[email protected]> wrote:
>>> Use fault_in_pages_readable() to prefault user context
>>> instead of open coding
>>>
>>> Signed-off-by: Christophe Leroy <[email protected]>
>>> ---
>>> arch/powerpc/kernel/signal_32.c | 13 +++++--------
>>> 1 file changed, 5 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
>>> index 492f03451877..cfacb2726152 100644
>>> --- a/arch/powerpc/kernel/signal_32.c
>>> +++ b/arch/powerpc/kernel/signal_32.c
>>> @@ -25,6 +25,7 @@
>>> #include <linux/errno.h>
>>> #include <linux/elf.h>
>>> #include <linux/ptrace.h>
>>> +#include <linux/pagemap.h>
>>> #include <linux/ratelimit.h>
>>> #ifdef CONFIG_PPC64
>>> #include <linux/syscalls.h>
>>> @@ -1045,7 +1046,6 @@ long sys_swapcontext(struct ucontext __user *old_ctx,
>>> struct ucontext __user *new_ctx,
>>> int ctx_size, int r6, int r7, int r8, struct pt_regs *regs)
>>> {
>>> - unsigned char tmp __maybe_unused;
>>> int ctx_has_vsx_region = 0;
>>>
>>> #ifdef CONFIG_PPC64
>>> @@ -1109,9 +1109,8 @@ long sys_swapcontext(struct ucontext __user *old_ctx,
>>> }
>>> if (new_ctx == NULL)
>>> return 0;
>>> - if (!access_ok(VERIFY_READ, new_ctx, ctx_size)
>>> - || __get_user(tmp, (u8 __user *) new_ctx)
>>> - || __get_user(tmp, (u8 __user *) new_ctx + ctx_size - 1))
>>> + if (!access_ok(VERIFY_READ, new_ctx, ctx_size) ||
>>> + fault_in_pages_readable((u8 __user *)new_ctx, ctx_size))
>>> return -EFAULT;
>>>
>>> /*
>>> @@ -1231,7 +1230,6 @@ int sys_debug_setcontext(struct ucontext __user *ctx,
>>> {
>>> struct sig_dbg_op op;
>>> int i;
>>> - unsigned char tmp __maybe_unused;
>>> unsigned long new_msr = regs->msr;
>>> #ifdef CONFIG_PPC_ADV_DEBUG_REGS
>>> unsigned long new_dbcr0 = current->thread.debug.dbcr0;
>>> @@ -1287,9 +1285,8 @@ int sys_debug_setcontext(struct ucontext __user *ctx,
>>> current->thread.debug.dbcr0 = new_dbcr0;
>>> #endif
>>>
>>> - if (!access_ok(VERIFY_READ, ctx, sizeof(*ctx))
>>> - || __get_user(tmp, (u8 __user *) ctx)
>>> - || __get_user(tmp, (u8 __user *) (ctx + 1) - 1))
>>> + if (!access_ok(VERIFY_READ, ctx, sizeof(*ctx)) ||
>>> + fault_in_pages_readable((u8 __user *)ctx, 1))
>>
>> I believe you meant:
>>
>> fault_in_pages_readable((u8 __user *)new_ctx, ctx_size)
>>
>> Since (u8 __user *) (ctx + 1) - 1 really is (u8 __user *) new_ctx + ctx_size - 1
>
> Without the copy/paste errors:
>
> [...]
> fault_in_pages_readable((u8 __user *)ctx, sizeof(*ctx))
>
> Since (u8 __user *) (ctx + 1) - 1 really is (u8 __user *) ctx + sizeof(*ctx) - 1
> [...]

Oops you're right thanks.
v2 submitted

Christophe


>>> return -EFAULT;
>>>
>>> /*
>>> --
>>> 2.13.3
>>>