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Mon, 23 Mar 2026 14:42:01 +0100 (CET) Message-ID: <176cfd181e783d2b24fad1a2c7b18425374b4622.camel@collabora.com> Subject: Re: [PATCH v2] media: v4l2-ctrls: validate HEVC slice reference lists From: Nicolas Dufresne To: Pengpeng Hou , mchehab@kernel.org Cc: hverkuil@kernel.org, sakari.ailus@linux.intel.com, laurent.pinchart@ideasonboard.com, opensource206@gmail.com, jernej.skrabec@gmail.com, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Date: Mon, 23 Mar 2026 09:41:58 -0400 In-Reply-To: <20260323083031.30941-1-pengpeng@iscas.ac.cn> References: <20260323083031.30941-1-pengpeng@iscas.ac.cn> Autocrypt: addr=nicolas.dufresne@collabora.com; prefer-encrypt=mutual; keydata=mDMEaCN2ixYJKwYBBAHaRw8BAQdAM0EHepTful3JOIzcPv6ekHOenE1u0vDG1gdHFrChD /e0J05pY29sYXMgRHVmcmVzbmUgPG5pY29sYXNAbmR1ZnJlc25lLmNhPoicBBMWCgBEAhsDBQsJCA cCAiICBhUKCQgLAgQWAgMBAh4HAheABQkJZfd1FiEE7w1SgRXEw8IaBG8S2UGUUSlgcvQFAmibrjo CGQEACgkQ2UGUUSlgcvQlQwD/RjpU1SZYcKG6pnfnQ8ivgtTkGDRUJ8gP3fK7+XUjRNIA/iXfhXMN abIWxO2oCXKf3TdD7aQ4070KO6zSxIcxgNQFtDFOaWNvbGFzIER1ZnJlc25lIDxuaWNvbGFzLmR1Z nJlc25lQGNvbGxhYm9yYS5jb20+iJkEExYKAEECGwMFCwkIBwICIgIGFQoJCAsCBBYCAwECHgcCF4 AWIQTvDVKBFcTDwhoEbxLZQZRRKWBy9AUCaCyyxgUJCWX3dQAKCRDZQZRRKWBy9ARJAP96pFmLffZ smBUpkyVBfFAf+zq6BJt769R0al3kHvUKdgD9G7KAHuioxD2v6SX7idpIazjzx8b8rfzwTWyOQWHC AAS0LU5pY29sYXMgRHVmcmVzbmUgPG5pY29sYXMuZHVmcmVzbmVAZ21haWwuY29tPoiZBBMWCgBBF iEE7w1SgRXEw8IaBG8S2UGUUSlgcvQFAmibrGYCGwMFCQll93UFCwkIBwICIgIGFQoJCAsCBBYCAw ECHgcCF4AACgkQ2UGUUSlgcvRObgD/YnQjfi4+L8f4fI7p1pPMTwRTcaRdy6aqkKEmKsCArzQBAK8 bRLv9QjuqsE6oQZra/RB4widZPvphs78H0P6NmpIJ Organization: Collabora Canada Content-Type: multipart/signed; micalg="pgp-sha512"; protocol="application/pgp-signature"; boundary="=-foqRranGiZytQIsq4ef3" User-Agent: Evolution 3.58.3 (3.58.3-1.fc43) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 --=-foqRranGiZytQIsq4ef3 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Le lundi 23 mars 2026 =C3=A0 16:30 +0800, Pengpeng Hou a =C3=A9crit=C2=A0: > HEVC slice parameters are shared stateless V4L2 controls, but the common > control validation path currently does not verify the active reference > counts or the ref_idx_l0/ref_idx_l1 entries before driver-specific code > uses them to index fixed 16-entry DPB arrays. >=20 > The original report was triggered by Cedrus, but the missing validation > is not Cedrus-specific. Move the bounds checks into the common HEVC slice > control validation path so every stateless HEVC driver gets the same > basic guarantees as soon as the control is queued. >=20 > Signed-off-by: Pengpeng Hou > --- > v2: > - move the validation from Cedrus-specific try_ctrl() into > =C2=A0 drivers/media/v4l2-core/v4l2-ctrls-core.c > - keep the checks limited to HEVC slice reference counts and indices >=20 > =C2=A0drivers/media/v4l2-core/v4l2-ctrls-core.c | 24 ++++++++++++++++++++= +++ > =C2=A01 file changed, 24 insertions(+) >=20 > diff --git a/drivers/media/v4l2-core/v4l2-ctrls-core.c b/drivers/media/v4= l2-core/v4l2-ctrls-core.c > index 6b375720e395..4e7563c8bf4a 100644 > --- a/drivers/media/v4l2-core/v4l2-ctrls-core.c > +++ b/drivers/media/v4l2-core/v4l2-ctrls-core.c > @@ -1260,6 +1260,30 @@ static int std_validate_compound(const struct v4l2= _ctrl *ctrl, u32 idx, > =C2=A0 break; > =C2=A0 > =C2=A0 case V4L2_CTRL_TYPE_HEVC_SLICE_PARAMS: > + p_hevc_slice_params =3D p; > + > + if (p_hevc_slice_params->num_ref_idx_l0_active_minus1 >=3D > + =C2=A0=C2=A0=C2=A0 V4L2_HEVC_DPB_ENTRIES_NUM_MAX) > + return -EINVAL; Ack. > + > + for (i =3D 0; i <=3D p_hevc_slice_params->num_ref_idx_l0_active_minus1= ; > + =C2=A0=C2=A0=C2=A0=C2=A0 i++) > + if (p_hevc_slice_params->ref_idx_l0[i] >=3D > + =C2=A0=C2=A0=C2=A0 V4L2_HEVC_DPB_ENTRIES_NUM_MAX) > + return -EINVAL; That one is a breaking change since userspace already passes off limit valu= es such as 0xff when a reference is missing (was lost). See: 47825b1646a6a9eca0f90baa3d4f98947c2add96 The hardware may or may not be capable of doing concealment, but with this change, we bring down all drivers to failing the decode completely. > + > + if (p_hevc_slice_params->slice_type !=3D V4L2_HEVC_SLICE_TYPE_B) > + break; > + > + if (p_hevc_slice_params->num_ref_idx_l1_active_minus1 >=3D > + =C2=A0=C2=A0=C2=A0 V4L2_HEVC_DPB_ENTRIES_NUM_MAX) > + return -EINVAL; Ack. > + > + for (i =3D 0; i <=3D p_hevc_slice_params->num_ref_idx_l1_active_minus1= ; > + =C2=A0=C2=A0=C2=A0=C2=A0 i++) > + if (p_hevc_slice_params->ref_idx_l1[i] >=3D > + =C2=A0=C2=A0=C2=A0 V4L2_HEVC_DPB_ENTRIES_NUM_MAX) > + return -EINVAL; Same. cheers, Nicolas > =C2=A0 break; > =C2=A0 > =C2=A0 case V4L2_CTRL_TYPE_HEVC_EXT_SPS_ST_RPS: --=-foqRranGiZytQIsq4ef3 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQTvDVKBFcTDwhoEbxLZQZRRKWBy9AUCacFDJwAKCRDZQZRRKWBy 9JXAAQCms2rvqcuvIHAxB0I9G5VvDbfJAN7tOfkMoYGnXFod2AEA17TBpISGNjZT llD8rgquch74tnNaJ+w1v9Mk6lczgQY= =ysQk -----END PGP SIGNATURE----- --=-foqRranGiZytQIsq4ef3--