fs/compat_ioctl.c: VIDEO_SET_SPU_PALETTE missing error check

The compat ioctl for VIDEO_SET_SPU_PALETTE was missing an error check
while converting ioctl arguments.  This could lead to leaking kernel
stack contents into userspace.

Patch extracted from existing fix in grsecurity.

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: David Miller <davem@davemloft.net>
Cc: Brad Spengler <spender@grsecurity.net>
Cc: PaX Team <pageexec@freemail.hu>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c
index f5054025f9da..4c6285fff598 100644
--- a/fs/compat_ioctl.c
+++ b/fs/compat_ioctl.c
@@ -210,6 +210,8 @@ static int do_video_set_spu_palette(unsigned int fd, unsigned int cmd,
 
         err  = get_user(palp, &up->palette);
         err |= get_user(length, &up->length);
+        if (err)
+                return -EFAULT;
 
         up_native = compat_alloc_user_space(sizeof(struct video_spu_palette));
         err  = put_user(compat_ptr(palp), &up_native->palette);