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([2405:201:31:d01f:1c4d:265b:8163:813b]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2ab29966d91sm55324925ad.45.2026.02.12.04.34.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Feb 2026 04:34:44 -0800 (PST) From: Soham Kute To: mchehab@kernel.org Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+ab12f0c08dd7ab8d057c@syzkaller.appspotmail.com, Soham Kute Subject: [PATCH] media: dvb-core: protect dvr_buffer reinitialization with lock Date: Thu, 12 Feb 2026 18:01:11 +0530 Message-Id: <20260212123111.12393-1-officialsohamkute@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" dvb_dvr_open() updates dvr_buffer fields without holding dmxdev->lock. This can race with concurrent readers and lead to inconsistent ringbuffer state. Protect dvr_buffer reinitialization with spin_lock_irq() to serialize against concurrent access. Reported-by: syzbot+ab12f0c08dd7ab8d057c@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3Dab12f0c08dd7ab8d057c Signed-off-by: Soham Kute --- drivers/media/dvb-core/dmxdev.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/media/dvb-core/dmxdev.c b/drivers/media/dvb-core/dmxde= v.c index 8c6f5aafd..e5e666866 100644 --- a/drivers/media/dvb-core/dmxdev.c +++ b/drivers/media/dvb-core/dmxdev.c @@ -168,7 +168,12 @@ static int dvb_dvr_open(struct inode *inode, struct fi= le *file) mutex_unlock(&dmxdev->mutex); return -ENOMEM; } - dvb_ringbuffer_init(&dmxdev->dvr_buffer, mem, DVR_BUFFER_SIZE); + spin_lock_irq(&dmxdev->lock); + dmxdev->dvr_buffer.data =3D mem; + dmxdev->dvr_buffer.size =3D DVR_BUFFER_SIZE; + dvb_ringbuffer_reset(&dmxdev->dvr_buffer); + spin_unlock_irq(&dmxdev->lock); + if (dmxdev->may_do_mmap) dvb_vb2_init(&dmxdev->dvr_vb2_ctx, "dvr", file->f_flags & O_NONBLOCK); --=20 2.34.1