fs/compat_ioctl.c: VIDEO_SET_SPU_PALETTE missing error check

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@chromium.org>
Cc: David Miller <davem@davemloft.net>
Cc: Brad Spengler <spender@grsecurity.net>
Cc: PaX Team <pageexec@freemail.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c
index 641640dc7ae54e7d55a86d4d149ac1ec54d3f92e..7a00d9b155bf9eabbbed6bfc157650743b6621f0 100644 (file)
--- a/fs/compat_ioctl.c
+++ b/fs/compat_ioctl.c
@@ -227,6 +227,8 @@ 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);