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MIPS: Compat: Use 32-bit wrapper for compat_sys_futex.

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We can't trust userspace to pass signed-extend arguments.  Not correctly
sign-extended arguments to futex-wait result in architecturally undefined
operation of 32-bit arithmetic instructions.

For example, if 'val' is too big and bit-31 is 1, the caller may enter
endless loop at:

futex_wait_setup()
{
	...

	if (uval != val) {
		queue_unlock(q, *hb);
		ret = -EWOULDBLOCK;

	...
}

Signed-off-by: Yong Zhang <yong.zhang@windriver.com>
To: linux-mips@linux-mips.org
To: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/2714/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Yong Zhang 2011-08-16 09:54:54 +08:00 committed by Ralf Baechle
parent b8ecf341f1
commit 1eec6cd08b
3 changed files with 9 additions and 2 deletions
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7
arch/mips/kernel/linux32.c
View file

@ -349,3 +349,10 @@ SYSCALL_DEFINE6(32_fanotify_mark, int, fanotify_fd, unsigned int, flags,
return sys_fanotify_mark(fanotify_fd, flags, merge_64(a3, a4),
dfd, pathname);
}
SYSCALL_DEFINE6(32_futex, u32 __user *, uaddr, int, op, u32, val,
struct compat_timespec __user *, utime, u32 __user *, uaddr2,
u32, val3)
{
return compat_sys_futex(uaddr, op, val, utime, uaddr2, val3);
}

2
arch/mips/kernel/scall64-n32.S
View file

@ -315,7 +315,7 @@ EXPORT(sysn32_call_table)
PTR sys_fremovexattr
PTR sys_tkill
PTR sys_ni_syscall
PTR compat_sys_futex
PTR sys_32_futex
PTR compat_sys_sched_setaffinity /* 6195 */
PTR compat_sys_sched_getaffinity
PTR sys_cacheflush

2
arch/mips/kernel/scall64-o32.S
View file

@ -441,7 +441,7 @@ sys_call_table:
PTR sys_fremovexattr /* 4235 */
PTR sys_tkill
PTR sys_sendfile64
PTR compat_sys_futex
PTR sys_32_futex
PTR compat_sys_sched_setaffinity
PTR compat_sys_sched_getaffinity /* 4240 */
PTR compat_sys_io_setup