dri: Protect against NULL dereference following GPU hang.

References:

  Bug 28361 - "glresize" causes server segfault with single buffering.
  https://bugs.freedesktop.org/show_bug.cgi?id=28361

[ 14528.767] (EE) intel(0): Failed to submit batch buffer, expect rendering corruption or even a frozen display: Input/output error.
[ 14528.767] (EE) intel(0): Disabling acceleration.
[ 14528.788] Backtrace:
[ 14528.858] 0: /usr/bin/X (xorg_backtrace+0x28) [0x491818]
[ 14528.858] 1: /usr/bin/X (0x400000+0x65ca9) [0x465ca9]
[ 14528.858] 2: /lib/libpthread.so.0 (0x7f9df2dc9000+0xedf0) [0x7f9df2dd7df0]
[ 14528.858] 3: /usr/local/lib/libdrm_intel.so.1 (drm_intel_bo_flink+0x0) [0x7f9defd60c60]
[ 14528.858] 4: /usr/local/lib/xorg/modules/drivers/intel_drv.so (0x7f9deff6a000+0x2fdfd) [0x7f9deff99dfd]
[ 14528.858] 5: /usr/lib/xorg/modules/extensions/libdri2.so (0x7f9df01b8000+0x19e7) [0x7f9df01b99e7]
[ 14528.858] 6: /usr/lib/xorg/modules/extensions/libdri2.so (0x7f9df01b8000+0x1fdb) [0x7f9df01b9fdb]
[ 14528.858] 7: /usr/lib/xorg/modules/extensions/libdri2.so (DRI2GetBuffersWithFormat+0x10) [0x7f9df01ba250]
[ 14528.858] 8: /usr/lib/xorg/modules/extensions/libdri2.so (0x7f9df01b8000+0x3834) [0x7f9df01bb834]
[ 14528.858] 9: /usr/bin/X (0x400000+0x2fc2c) [0x42fc2c]
[ 14528.858] 10: /usr/bin/X (0x400000+0x24da5) [0x424da5]
[ 14528.858] 11: /lib/libc.so.6 (__libc_start_main+0xe6) [0x7f9df1d60a26]
[ 14528.858] 12: /usr/bin/X (0x400000+0x24959) [0x424959]
[ 14528.858] Segmentation fault at address 0x20
[ 14528.858] Fatal server error:
[ 14528.858] Caught signal 11 (Segmentation fault). Server aborting

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
(cherry picked from commit 6db1e5231b7a0e79611f771d4efea686f7849e04)

Signed-off-by: Owain G. Ainsworth <oga@openbsd.org>

0 files changed, 0 insertions, 0 deletions