MIPS: Compat: Use 32-bit wrapper for compat_sys_futex.
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>
diff --git a/arch/mips/kernel/linux32.c b/arch/mips/kernel/linux32.c
index 876a75c..922a554 100644
--- a/arch/mips/kernel/linux32.c
+++ b/arch/mips/kernel/linux32.c
@@ -349,3 +349,10 @@
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);
+}
diff --git a/arch/mips/kernel/scall64-n32.S b/arch/mips/kernel/scall64-n32.S
index f9296e8..6de1f59 100644
--- a/arch/mips/kernel/scall64-n32.S
+++ b/arch/mips/kernel/scall64-n32.S
@@ -315,7 +315,7 @@
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
diff --git a/arch/mips/kernel/scall64-o32.S b/arch/mips/kernel/scall64-o32.S
index 4d7c982..1d81316 100644
--- a/arch/mips/kernel/scall64-o32.S
+++ b/arch/mips/kernel/scall64-o32.S
@@ -441,7 +441,7 @@
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