[Dapper] [CVE-2010-4078] [PATCH 1/1] drivers/video/sis/sis_main.c: prevent reading uninitialized stack memory, CVE-2010-4078

Brad Figg brad.figg at canonical.com
Tue Jan 25 20:42:23 UTC 2011

From: Dan Rosenberg <drosenberg at vsecurity.com>


BugLink: http://bugs.launchpad.net/bugs/707579

Released by: 2.6.35.y stable upstream
             2.6.32.y stable 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 at gmail.com>
Cc: Thomas Winischhofer <thomas at winischhofer.net>
Cc: <stable at kernel.org>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>

(cherry-picked from commit fd02db9de73faebc51240619c7c7f99bee9f65c7)
Signed-off-by: Brad Figg <brad.figg at canonical.com>
 drivers/video/sis/sis_main.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/drivers/video/sis/sis_main.c b/drivers/video/sis/sis_main.c
index 559bf17..b52f8e4 100644
--- 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 *info, unsigned int cmd,

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


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