On Tue, Mar 28, 2023 at 05:36:27PM +0800, Min Li wrote:

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

I think we should also add

Fixes: f89823c21224 ("drm/i915/perf: Implement I915_PERF_ADD/REMOVE_CONFIG interface") Cc: stable@vger.kernel.org # v4.14+

Andi

---

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 824a34ec0b83..93748ca2c5da 100644 --- a/drivers/gpu/drm/i915/i915_perf.c +++ b/drivers/gpu/drm/i915/i915_perf.c @@ -4634,13 +4634,13 @@ 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); -- 2.25.1