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Thu, 16 Apr 2026 21:14:22 -0700 (PDT) Message-ID: <7a3eac3d-d44b-48db-af68-c5f0087a8ac2@gmail.com> Date: Fri, 17 Apr 2026 00:14:10 -0400 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:136.0) Gecko/20100101 Thunderbird/136.0 Subject: Re: [PATCH] drm/auth: Only drm_drop_master if it exists To: Jonathan Cavitt , dri-devel@lists.freedesktop.org Cc: saurabhg.gupta@intel.com, alex.zuo@intel.com, linux-kernel@vger.kernel.org, maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmerman@suse.de, airlied@gmail.com, simona@ffwll.ch References: <20260416210047.3904106-1-jonathan.cavitt@intel.com> Content-Language: en-CA, en-US From: Luben Tuikov Autocrypt: addr=ltuikov89@gmail.com; keydata= xjMEZTohOhYJKwYBBAHaRw8BAQdAWSq76k+GsENjDTMVCy9Vr4fAO9Rb57/bPT1APnbnnRHN Ikx1YmVuIFR1aWtvdiA8bHR1aWtvdjg5QGdtYWlsLmNvbT7CmQQTFgoAQRYhBJkj7+VmFO9b eaAl10wVR5QxozSvBQJlOiE6AhsDBQkJZgGABQsJCAcCAiICBhUKCQgLAgQWAgMBAh4HAheA AAoJEEwVR5QxozSvSm4BAOwCpX53DTQhE20FBGlTMqKCOQyJqlMcIQ9SO1qPWX1iAQCv3vfy JwktF7REl1yt7IU2Sye1qmQMfJxdt9JMbMNNBs44BGU6IToSCisGAQQBl1UBBQEBB0BT9wSP cCE8uGe7FWo8C+nTSyWPXKTx9F0gpEnlqReRBwMBCAfCfgQYFgoAJhYhBJkj7+VmFO9beaAl 10wVR5QxozSvBQJlOiE6AhsMBQkJZgGAAAoJEEwVR5QxozSvSsYA/2LIFjbxQ2ikbU5S0pKo aMDzO9eGz69uNhNWJcvIKJK6AQC9228Mqc1JeZMIyjYWr2HKYHi8S2q2/zHrSZwAWYYwDA== In-Reply-To: <20260416210047.3904106-1-jonathan.cavitt@intel.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="------------eGCYUJsiqbjrkWPuTj7xBSVH" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --------------eGCYUJsiqbjrkWPuTj7xBSVH Content-Type: multipart/mixed; boundary="------------80IG00mtfce8l4iguWXcf60q"; protected-headers="v1" From: Luben Tuikov To: Jonathan Cavitt , dri-devel@lists.freedesktop.org Cc: saurabhg.gupta@intel.com, alex.zuo@intel.com, linux-kernel@vger.kernel.org, maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmerman@suse.de, airlied@gmail.com, simona@ffwll.ch Message-ID: <7a3eac3d-d44b-48db-af68-c5f0087a8ac2@gmail.com> Subject: Re: [PATCH] drm/auth: Only drm_drop_master if it exists References: <20260416210047.3904106-1-jonathan.cavitt@intel.com> In-Reply-To: <20260416210047.3904106-1-jonathan.cavitt@intel.com> --------------80IG00mtfce8l4iguWXcf60q Content-Type: multipart/mixed; boundary="------------qh8o00ewZwPUOnqao5LNfmQ6" --------------qh8o00ewZwPUOnqao5LNfmQ6 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 2026-04-16 17:00, Jonathan Cavitt wrote: > It is possible that both dev->master and file_priv->master are NULL whe= n > passed to drm_master_release, which would result in dev being passed to= > drm_drop_master (as NULL =3D=3D NULL here). This would result in a NUL= L > pointer dereference when passing dev->master to drm_master_put in > drm_drop_master. >=20 > Only call drm_drop_master if dev->master exists. Also, make sure the > original calling requirement is maintained (dev->master =3D=3D > file_priv->master). >=20 > This fixes a static analysis issue. >=20 > Signed-off-by: Jonathan Cavitt > Cc: Maarten Lankhorst > Cc: Maxime Ripard > Cc: Thomas Zimmermann > Cc: David Airlie > Cc: Simona Vetter > --- > drivers/gpu/drm/drm_auth.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) >=20 > diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c > index e17bb0f1f9e0..e5013b870ba0 100644 > --- a/drivers/gpu/drm/drm_auth.c > +++ b/drivers/gpu/drm/drm_auth.c > @@ -347,7 +347,7 @@ void drm_master_release(struct drm_file *file_priv)= > if (!drm_is_current_master_locked(file_priv)) > goto out; > =20 > - if (dev->master =3D=3D file_priv->master) > + if (dev->master && dev->master =3D=3D file_priv->master) > drm_drop_master(dev, file_priv); > out: > if (drm_core_check_feature(dev, DRIVER_MODESET) && file_priv->is_mast= er) { This is a good catch. Acked-by: Luben Tuikov --=20 Regards, Luben --------------qh8o00ewZwPUOnqao5LNfmQ6 Content-Type: application/pgp-keys; name="OpenPGP_0x4C15479431A334AF.asc" Content-Disposition: attachment; filename="OpenPGP_0x4C15479431A334AF.asc" Content-Description: OpenPGP public key Content-Transfer-Encoding: quoted-printable -----BEGIN PGP PUBLIC KEY BLOCK----- xjMEZTohOhYJKwYBBAHaRw8BAQdAWSq76k+GsENjDTMVCy9Vr4fAO9Rb57/bPT1A PnbnnRHNIkx1YmVuIFR1aWtvdiA8bHR1aWtvdjg5QGdtYWlsLmNvbT7CmQQTFgoA QRYhBJkj7+VmFO9beaAl10wVR5QxozSvBQJlOiE6AhsDBQkJZgGABQsJCAcCAiIC BhUKCQgLAgQWAgMBAh4HAheAAAoJEEwVR5QxozSvSm4BAOwCpX53DTQhE20FBGlT MqKCOQyJqlMcIQ9SO1qPWX1iAQCv3vfyJwktF7REl1yt7IU2Sye1qmQMfJxdt9JM bMNNBs44BGU6IToSCisGAQQBl1UBBQEBB0BT9wSPcCE8uGe7FWo8C+nTSyWPXKTx 9F0gpEnlqReRBwMBCAfCfgQYFgoAJhYhBJkj7+VmFO9beaAl10wVR5QxozSvBQJl OiE6AhsMBQkJZgGAAAoJEEwVR5QxozSvSsYA/2LIFjbxQ2ikbU5S0pKoaMDzO9eG z69uNhNWJcvIKJK6AQC9228Mqc1JeZMIyjYWr2HKYHi8S2q2/zHrSZwAWYYwDA=3D=3D =3DqCaZ -----END PGP PUBLIC KEY BLOCK----- --------------qh8o00ewZwPUOnqao5LNfmQ6-- --------------80IG00mtfce8l4iguWXcf60q-- --------------eGCYUJsiqbjrkWPuTj7xBSVH Content-Type: application/pgp-signature; name="OpenPGP_signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="OpenPGP_signature.asc" -----BEGIN PGP SIGNATURE----- wnsEABYIACMWIQSZI+/lZhTvW3mgJddMFUeUMaM0rwUCaeGzkgUDAAAAAAAKCRBMFUeUMaM0r4no AQCNQRCa7yk0UYHIkBddv6B3zVm/fGmFJ+F3ykOma+BSTwD/eVDNMx7CdumavDwJwnKAY5uXt6Ba iPXa1B6i76zPBw0= =JU5P -----END PGP SIGNATURE----- --------------eGCYUJsiqbjrkWPuTj7xBSVH--