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drm/i915: Fix use after free in logical_render_ring_init

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Commit 3b3f1650b1 ("drm/i915: Allocate intel_engine_cs
structure only for the enabled engines") introduced the
dynanically allocated engine instances and created an
potential use after free scenario in logical_render_ring_init
where lrc_destroy_wa_ctx_obj could be called after the engine
instance has been freed.

This can only happen during engine setup/init error handling
which luckily does not happen ever in practice.

Fix is to not call lrc_destroy_wa_ctx_obj since it would have
already been executed from the preceding engine cleanup.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 3b3f1650b1 ("drm/i915: Allocate intel_engine_cs structure only for the enabled engines")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1481894322-2145-1-git-send-email-tvrtko.ursulin@linux.intel.com
(cherry picked from commit d038fc7e4f)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
This commit is contained in:
Tvrtko Ursulin 2016-12-16 13:18:42 +00:00 committed by Jani Nikula
parent 1c4672ce4e
commit d8953c8326
1 changed files with 1 additions and 6 deletions
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7
drivers/gpu/drm/i915/intel_lrc.c
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@ -1968,12 +1968,7 @@ int logical_render_ring_init(struct intel_engine_cs *engine)
ret);
}
ret = logical_ring_init(engine);
if (ret) {
lrc_destroy_wa_ctx_obj(engine);
}
return ret;
return logical_ring_init(engine);
}
int logical_xcs_ring_init(struct intel_engine_cs *engine)