Author: emaste
Date: Thu Mar 22 01:00:55 2018
New Revision: 331339
URL: https://svnweb.freebsd.org/changeset/base/331339
Log:
Correct signedness bug in drm_modeset_ctl
drm_modeset_ctl() takes a signed in from userland, does a boundscheck,
and then uses it to index into a structure and write to it. The
boundscheck only checks upper bound, and never checks for nagative
values. If the int coming from userland is negative [after conversion]
it will bypass the boundscheck, perform a negative index into an array
and write to it, causing memory corruption.
Note that this is in the "old" drm driver; this issue does not exist
in drm2.
Reported by: Ilja Van Sprundel <ivansprun...@ioactive.com>
Reviewed by: cem
MFC after: 1 day
Sponsored by: The FreeBSD Foundation
Modified:
head/sys/dev/drm/drm_irq.c
Modified: head/sys/dev/drm/drm_irq.c
==============================================================================
--- head/sys/dev/drm/drm_irq.c Thu Mar 22 00:55:36 2018 (r331338)
+++ head/sys/dev/drm/drm_irq.c Thu Mar 22 01:00:55 2018 (r331339)
@@ -351,7 +351,7 @@ int drm_modeset_ctl(struct drm_device *dev, void *data
goto out;
crtc = modeset->crtc;
- if (crtc >= dev->num_crtcs) {
+ if (crtc < 0 || crtc >= dev->num_crtcs) {
ret = EINVAL;
goto out;
}
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