Hi Min, 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@xxxxxxxxx> Thank you for your patch! Reviewed-by: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx> 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
