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>
I think we should also add
Fixes: f89823c21224 ("drm/i915/perf: Implement I915_PERF_ADD/REMOVE_CONFIG interface")
Cc: <stable@xxxxxxxxxxxxxxx> # 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
