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* [PATCH] csky: fix syscall_get_arguments() and syscall_set_arguments()
@ 2019-03-29 17:12 Dmitry V. Levin
  2019-03-30  0:49 ` Guo Ren
  0 siblings, 1 reply; 2+ messages in thread
From: Dmitry V. Levin @ 2019-03-29 17:12 UTC (permalink / raw)
  To: Guo Ren
  Cc: Steven Rostedt, Ingo Molnar, Kees Cook, Andy Lutomirski,
	Will Drewry, linux-kernel

C-SKY syscall arguments are located in orig_a0,a1,a2,a3,regs[0],regs[1]
fields of struct pt_regs.

Due to an off-by-one bug and a bug in pointer arithmetic
syscall_get_arguments() was reading orig_a0,regs[1..5] fields instead.
Likewise, syscall_set_arguments() was writing orig_a0,regs[1..5] fields
instead.

Fixes: 4859bfca11c7d ("csky: System Call")
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Will Drewry <wad@chromium.org>
Cc: stable@vger.kernel.org # v4.20+
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
---
 arch/csky/include/asm/syscall.h | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/csky/include/asm/syscall.h b/arch/csky/include/asm/syscall.h
index d637445737b7..9a9cd81e66c1 100644
--- a/arch/csky/include/asm/syscall.h
+++ b/arch/csky/include/asm/syscall.h
@@ -49,10 +49,11 @@ syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
 	if (i == 0) {
 		args[0] = regs->orig_a0;
 		args++;
-		i++;
 		n--;
+	} else {
+		i--;
 	}
-	memcpy(args, &regs->a1 + i * sizeof(regs->a1), n * sizeof(args[0]));
+	memcpy(args, &regs->a1 + i, n * sizeof(args[0]));
 }
 
 static inline void
@@ -63,10 +64,11 @@ syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
 	if (i == 0) {
 		regs->orig_a0 = args[0];
 		args++;
-		i++;
 		n--;
+	} else {
+		i--;
 	}
-	memcpy(&regs->a1 + i * sizeof(regs->a1), args, n * sizeof(regs->a0));
+	memcpy(&regs->a1 + i, args, n * sizeof(regs->a1));
 }
 
 static inline int
-- 
ldv

^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [PATCH] csky: fix syscall_get_arguments() and syscall_set_arguments()
  2019-03-29 17:12 [PATCH] csky: fix syscall_get_arguments() and syscall_set_arguments() Dmitry V. Levin
@ 2019-03-30  0:49 ` Guo Ren
  0 siblings, 0 replies; 2+ messages in thread
From: Guo Ren @ 2019-03-30  0:49 UTC (permalink / raw)
  To: Dmitry V. Levin
  Cc: Steven Rostedt, Ingo Molnar, Kees Cook, Andy Lutomirski,
	Will Drewry, linux-kernel

Thx Dmitry,

It works for me.

Tested-by: Guo Ren <ren_guo@c-sky.com>
Acked-by: Guo Ren <ren_guo@c-sky.com>

On Fri, Mar 29, 2019 at 08:12:30PM +0300, Dmitry V. Levin wrote:
> C-SKY syscall arguments are located in orig_a0,a1,a2,a3,regs[0],regs[1]
> fields of struct pt_regs.
> 
> Due to an off-by-one bug and a bug in pointer arithmetic
> syscall_get_arguments() was reading orig_a0,regs[1..5] fields instead.
> Likewise, syscall_set_arguments() was writing orig_a0,regs[1..5] fields
> instead.
> 
> Fixes: 4859bfca11c7d ("csky: System Call")
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Andy Lutomirski <luto@amacapital.net>
> Cc: Will Drewry <wad@chromium.org>
> Cc: stable@vger.kernel.org # v4.20+
> Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
> ---
>  arch/csky/include/asm/syscall.h | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/csky/include/asm/syscall.h b/arch/csky/include/asm/syscall.h
> index d637445737b7..9a9cd81e66c1 100644
> --- a/arch/csky/include/asm/syscall.h
> +++ b/arch/csky/include/asm/syscall.h
> @@ -49,10 +49,11 @@ syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
>  	if (i == 0) {
>  		args[0] = regs->orig_a0;
>  		args++;
> -		i++;
>  		n--;
> +	} else {
> +		i--;
>  	}
> -	memcpy(args, &regs->a1 + i * sizeof(regs->a1), n * sizeof(args[0]));
> +	memcpy(args, &regs->a1 + i, n * sizeof(args[0]));
>  }
>  
>  static inline void
> @@ -63,10 +64,11 @@ syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
>  	if (i == 0) {
>  		regs->orig_a0 = args[0];
>  		args++;
> -		i++;
>  		n--;
> +	} else {
> +		i--;
>  	}
> -	memcpy(&regs->a1 + i * sizeof(regs->a1), args, n * sizeof(regs->a0));
> +	memcpy(&regs->a1 + i, args, n * sizeof(regs->a1));
>  }
>  
>  static inline int
> -- 
> ldv

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2019-03-29 17:12 [PATCH] csky: fix syscall_get_arguments() and syscall_set_arguments() Dmitry V. Levin
2019-03-30  0:49 ` Guo Ren

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