From: Min Li lm0963hack@gmail.com
[ Upstream commit dc30c011469165d57af9adac5baff7d767d20e5c ]
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-lm0963ha... [tursulin: Manually added stable tag.] (cherry picked from commit 49f6f6483b652108bcb73accd0204a464b922395) Signed-off-by: Jani Nikula jani.nikula@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/i915/i915_perf.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c index 4b57cc10bd68e..774d45142091b 100644 --- a/drivers/gpu/drm/i915/i915_perf.c +++ b/drivers/gpu/drm/i915/i915_perf.c @@ -4220,13 +4220,13 @@ int i915_perf_add_config_ioctl(struct drm_device *dev, void *data, err = oa_config->id; goto sysfs_err; } - - mutex_unlock(&perf->metrics_lock); + id = oa_config->id;
drm_dbg(&perf->i915->drm, "Added config %s id=%i\n", oa_config->uuid, oa_config->id); + mutex_unlock(&perf->metrics_lock);
- return oa_config->id; + return id;
sysfs_err: mutex_unlock(&perf->metrics_lock);