From b9f0aee83335db1f3915f4e42a5e21b351740afd Mon Sep 17 00:00:00 2001 From: Dave Airlie Date: Tue, 17 Aug 2010 14:46:00 +1000 Subject: [PATCH] drm: stop information leak of old kernel stack. non-critical issue, CVE-2010-2803 Userspace controls the amount of memory to be allocate, so it can get the ioctl to allocate more memory than the kernel uses, and get access to kernel stack. This can only be done for processes authenticated to the X server for DRI access, and if the user has DRI access. Fix is to just memset the data to 0 if the user doesn't copy into it in the first place. Reported-by: Kees Cook Signed-off-by: Dave Airlie --- drivers/gpu/drm/drm_drv.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c index 90288ec7c284..3644c94c0a17 100644 --- a/drivers/gpu/drm/drm_drv.c +++ b/drivers/gpu/drm/drm_drv.c @@ -477,7 +477,9 @@ long drm_ioctl(struct file *filp, retcode = -EFAULT; goto err_i1; } - } + } else + memset(kdata, 0, _IOC_SIZE(cmd)); + if (ioctl->flags & DRM_UNLOCKED) retcode = func(dev, kdata, file_priv); else {