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If first drm_open fails, the error-handling path will incorrectly restore inode's mapping to NULL. This can cause the crash later on. Fix by separately storing away mapping pointers that drm_open can touch and restore each from its own respective variable if the call fails. Fixes: https://bugzilla.novell.com/show_bug.cgi?id=807850 (thanks to Michal Hocko for investigating investigating and finding the root cause of the bug) Reference: http://lists.freedesktop.org/archives/dri-devel/2013-March/036564.html v2: Use one variable to store file and inode mapping since they are the same at the function entry. Fix spelling mistakes in commit message. v3: Add reference to the original bug report. Reported-by: Marco Munderloh <munderl@tnt.uni-hannover.de> Tested-by: Marco Munderloh <munderl@tnt.uni-hannover.de> Signed-off-by: Ilija Hadzic <ihadzic@research.bell-labs.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: stable@vger.kernel.org Signed-off-by: Dave Airlie <airlied@redhat.com>
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* For the very latest on DRI development, please see: *
* http://dri.freedesktop.org/ *
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The Direct Rendering Manager (drm) is a device-independent kernel-level
device driver that provides support for the XFree86 Direct Rendering
Infrastructure (DRI).
The DRM supports the Direct Rendering Infrastructure (DRI) in four major
ways:
1. The DRM provides synchronized access to the graphics hardware via
the use of an optimized two-tiered lock.
2. The DRM enforces the DRI security policy for access to the graphics
hardware by only allowing authenticated X11 clients access to
restricted regions of memory.
3. The DRM provides a generic DMA engine, complete with multiple
queues and the ability to detect the need for an OpenGL context
switch.
4. The DRM is extensible via the use of small device-specific modules
that rely extensively on the API exported by the DRM module.
Documentation on the DRI is available from:
http://dri.freedesktop.org/wiki/Documentation
http://sourceforge.net/project/showfiles.php?group_id=387
http://dri.sourceforge.net/doc/
For specific information about kernel-level support, see:
The Direct Rendering Manager, Kernel Support for the Direct Rendering
Infrastructure
http://dri.sourceforge.net/doc/drm_low_level.html
Hardware Locking for the Direct Rendering Infrastructure
http://dri.sourceforge.net/doc/hardware_locking_low_level.html
A Security Analysis of the Direct Rendering Infrastructure
http://dri.sourceforge.net/doc/security_low_level.html