drm/i915: fix race condition UAF in i915_perf_add_config_ioctl
Userspace can guess the id value and try to race oa_config object creation with config remove, resulting in a use-after-free if we dereference the object after unlocking the metrics_lock. For that reason, unlocking the metrics_lock must be done after we are done dereferencing the object. Signed-off-by: Min Li <lm0963hack@gmail.com> Fixes: f89823c21224 ("drm/i915/perf: Implement I915_PERF_ADD/REMOVE_CONFIG interface") Cc: <stable@vger.kernel.org> # v4.14+ Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com> Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20230328093627.5067-1-lm0963hack@gmail.com [tursulin: Manually added stable tag.] (cherry picked from commit 49f6f6483b652108bcb73accd0204a464b922395) Signed-off-by: Jani Nikula <jani.nikula@intel.com>
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@ -4638,13 +4638,13 @@ int i915_perf_add_config_ioctl(struct drm_device *dev, void *data,
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err = oa_config->id;
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goto sysfs_err;
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}
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mutex_unlock(&perf->metrics_lock);
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id = oa_config->id;
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drm_dbg(&perf->i915->drm,
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"Added config %s id=%i\n", oa_config->uuid, oa_config->id);
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mutex_unlock(&perf->metrics_lock);
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return oa_config->id;
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return id;
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sysfs_err:
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mutex_unlock(&perf->metrics_lock);
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