[PATCH 260/270] fs/compat_ioctl.c: VIDEO_SET_SPU_PALETTE missing error check

[Herton Ronaldo Krzesinski]

3.5.7u1 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Kees Cook <keescook at chromium.org>

commit 12176503366885edd542389eed3aaf94be163fdb upstream.

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 at chromium.org>
Cc: David Miller <davem at davemloft.net>
Cc: Brad Spengler <spender at grsecurity.net>
Cc: PaX Team <pageexec at freemail.hu>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 fs/compat_ioctl.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c
index debdfe0..5d2069f 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);
-- 
1.7.9.5