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SubjectRe: [PATCH 1/1] drm/i915: fix race condition UAF in i915_perf_add_config_ioctl
On Tue, Mar 28, 2023 at 02:08:47PM +0100, Tvrtko Ursulin wrote:
>
>On 28/03/2023 10:36, 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>
>
>Fixes: f89823c21224 ("drm/i915/perf: Implement I915_PERF_ADD/REMOVE_CONFIG interface")
>Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
>Cc: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
>Cc: <stable@vger.kernel.org> # v4.14+
>
>>---
>> 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);
>
>LGTM.
>
>Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>
>Umesh or Lionel could you please double check? I can merge if confirmed okay.

LGTM,

Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>

Thanks,
Umesh

>
>Regards,
>
>Tvrtko

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