From: Min Li <lm0963hack@xxxxxxxxx>
commit dc30c011469165d57af9adac5baff7d767d20e5c upstream.
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@xxxxxxxxx>
Fixes: f89823c21224 ("drm/i915/perf: Implement I915_PERF_ADD/REMOVE_CONFIG interface")
Cc: <stable@xxxxxxxxxxxxxxx> # v4.14+
Reviewed-by: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx>
Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@xxxxxxxxx>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20230328093627.5067-1-lm0963hack@xxxxxxxxx
[tursulin: Manually added stable tag.]
(cherry picked from commit 49f6f6483b652108bcb73accd0204a464b922395)
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_perf.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -4612,13 +4612,13 @@ int i915_perf_add_config_ioctl(struct dr
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);
