[41/80] drivers/video/sis/sis_main.c: prevent reading uninitialized stack memory

Greg KH
2010-09-24T16:53:42Z

From: Dan Rosenberg <drosenberg@vsecurity.com>

commit fd02db9de73faebc51240619c7c7f99bee9f65c7 upstream.

The FBIOGET_VBLANK device ioctl allows unprivileged users to read 16 bytes
of uninitialized stack memory, because the "reserved" member of the
fb_vblank struct declared on the stack is not altered or zeroed before
being copied back to the user. This patch takes care of it.

Signed-off-by: Dan Rosenberg <dan.j.rosenberg@gmail.com>
Cc: Thomas Winischhofer <thomas@winischhofer.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/video/sis/sis_main.c | 3 +++
1 file changed, 3 insertions(+)

--- a/drivers/video/sis/sis_main.c
+++ b/drivers/video/sis/sis_main.c
@@ -1701,6 +1701,9 @@ static int sisfb_ioctl(struct fb_info *i
break;

case FBIOGET_VBLANK:
+
+ memset(&sisvbblank, 0, sizeof(struct fb_vblank));
+
sisvbblank.count = 0;
sisvbblank.flags = sisfb_setupvbblankflags(ivideo, &sisvbblank.vcount, &sisvbblank.hcount);