[PATCH] parisc: compat Fix siginfo_t -> compat_siginfo_t conversion on big endian

[PATCH] parisc: compat Fix siginfo_t -> compat_siginfo_t conversion on big endian

[Helge Deller]

This patch is basically the same as commit 9d42d48 from Catalin Marinas
but adopted to the parisc architecture.

The native (64-bit) sigval_t union contains sival_int (32-bit) and sival_ptr
(64-bit). When a compat application invokes a syscall that takes a sigval_t
value (as part of a larger structure, e.g.  compat_sys_mq_notify,
compat_sys_timer_create), the compat_sigval_t union is converted to the native
sigval_t with sival_int overlapping with either the least or the most
significant half of sival_ptr, depending on endianness. When the corresponding
signal is delivered to a compat application, on big endian the current
(compat_uptr_t)sival_ptr cast always returns 0 since sival_int corresponds to
the top part of sival_ptr. This patch fixes copy_siginfo_to_user32() so that
sival_int is copied to the compat_siginfo_t structure.

Cc: <stable@vger.kernel.org>
Reported-by: Bamvor Jian Zhang <bamvor.zhangjian@huawei.com>
Signed-off-by: Helge Deller <deller@gmx.de>

diff --git a/arch/parisc/kernel/signal32.c b/arch/parisc/kernel/signal32.c
index 984abbe..d1f1fcd 100644
--- a/arch/parisc/kernel/signal32.c
+++ b/arch/parisc/kernel/signal32.c
@@ -322,7 +322,6 @@ int
 copy_siginfo_to_user32 (compat_siginfo_t __user *to, const siginfo_t *from)
 {
 	compat_uptr_t addr;
-	compat_int_t val;
 	int err;
 
 	if (!access_ok(VERIFY_WRITE, to, sizeof(compat_siginfo_t)))
@@ -361,15 +360,13 @@ copy_siginfo_to_user32 (compat_siginfo_t __user *to, const siginfo_t *from)
 		case __SI_TIMER >> 16:
 			err |= __put_user(from->si_tid, &to->si_tid);
 			err |= __put_user(from->si_overrun, &to->si_overrun);
-			val = (compat_int_t)from->si_int;
-			err |= __put_user(val, &to->si_int);
+			err |= __put_user(from->si_int, &to->si_int);
 			break;
 		case __SI_RT >> 16:	/* Not generated by the kernel as of now.  */
 		case __SI_MESGQ >> 16:
 			err |= __put_user(from->si_uid, &to->si_uid);
 			err |= __put_user(from->si_pid, &to->si_pid);
-			val = (compat_int_t)from->si_int;
-			err |= __put_user(val, &to->si_int);
+			err |= __put_user(from->si_int, &to->si_int);
 			break;
 		}
 	}

Re: [PATCH] parisc: compat Fix siginfo_t -> compat_siginfo_t conversion on big endian

[Catalin Marinas]

On Sun, Mar 15, 2015 at 08:00:41PM +0000, Helge Deller wrote:
> This patch is basically the same as commit 9d42d48 from Catalin Marinas
> but adopted to the parisc architecture.
> 
> The native (64-bit) sigval_t union contains sival_int (32-bit) and sival_ptr
> (64-bit). When a compat application invokes a syscall that takes a sigval_t
> value (as part of a larger structure, e.g.  compat_sys_mq_notify,
> compat_sys_timer_create), the compat_sigval_t union is converted to the native
> sigval_t with sival_int overlapping with either the least or the most
> significant half of sival_ptr, depending on endianness. When the corresponding
> signal is delivered to a compat application, on big endian the current
> (compat_uptr_t)sival_ptr cast always returns 0 since sival_int corresponds to
> the top part of sival_ptr. This patch fixes copy_siginfo_to_user32() so that
> sival_int is copied to the compat_siginfo_t structure.

Se below, I don't think this patch is needed.

> diff --git a/arch/parisc/kernel/signal32.c b/arch/parisc/kernel/signal32.c
> index 984abbe..d1f1fcd 100644
> --- a/arch/parisc/kernel/signal32.c
> +++ b/arch/parisc/kernel/signal32.c
> @@ -322,7 +322,6 @@ int
>  copy_siginfo_to_user32 (compat_siginfo_t __user *to, const siginfo_t *from)
>  {
>  	compat_uptr_t addr;
> -	compat_int_t val;
>  	int err;
>  
>  	if (!access_ok(VERIFY_WRITE, to, sizeof(compat_siginfo_t)))
> @@ -361,15 +360,13 @@ copy_siginfo_to_user32 (compat_siginfo_t __user *to, const siginfo_t *from)
>  		case __SI_TIMER >> 16:
>  			err |= __put_user(from->si_tid, &to->si_tid);
>  			err |= __put_user(from->si_overrun, &to->si_overrun);
> -			val = (compat_int_t)from->si_int;
> -			err |= __put_user(val, &to->si_int);
> +			err |= __put_user(from->si_int, &to->si_int);

Is there any actual change here? The native si_int is 32-bit already,
same as compat_int_t. I didn't think parisc needed fixing (only if it
was using si_ptr which is 64-bit on a 64-bit architecture).

>  			break;
>  		case __SI_RT >> 16:	/* Not generated by the kernel as of now.  */
>  		case __SI_MESGQ >> 16:
>  			err |= __put_user(from->si_uid, &to->si_uid);
>  			err |= __put_user(from->si_pid, &to->si_pid);
> -			val = (compat_int_t)from->si_int;
> -			err |= __put_user(val, &to->si_int);
> +			err |= __put_user(from->si_int, &to->si_int);

Same here.

-- 
Catalin