2019-03-29 17:13:51

by Dmitry V. Levin

Subject: [PATCH] csky: fix syscall_get_arguments() and syscall_set_arguments()

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 <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Will Drewry <[email protected]>
Cc: [email protected] # v4.20+
Signed-off-by: Dmitry V. Levin <[email protected]>
---
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

2019-03-30 00:50:52

by Guo Ren

Subject: Re: [PATCH] csky: fix syscall_get_arguments() and syscall_set_arguments()

Thx Dmitry,

It works for me.

Tested-by: Guo Ren <[email protected]>
Acked-by: Guo Ren <[email protected]>

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 <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Kees Cook <[email protected]>
> Cc: Andy Lutomirski <[email protected]>
> Cc: Will Drewry <[email protected]>
> Cc: [email protected] # v4.20+
> Signed-off-by: Dmitry V. Levin <[email protected]>
> ---
> 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