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([2405:201:682f:383f:3191:a257:32a3:b02c]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c7976f8f370sm13748370a12.7.2026.04.22.07.47.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Apr 2026 07:47:44 -0700 (PDT) From: Deepanshu Kartikey To: mchehab@kernel.org Cc: kees@kernel.org, peda@axentia.se, wsa@kernel.org, crope@iki.fi, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Deepanshu Kartikey , stable@vger.kernel.org, syzbot+019ced393ab913002b75@syzkaller.appspotmail.com Subject: [PATCH v3] media: rtl2832: fix use-after-free in rtl2832_remove() Date: Wed, 22 Apr 2026 20:17:34 +0530 Message-ID: <20260422144734.25650-1-kartikey406@gmail.com> X-Mailer: git-send-email 2.43.0 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" cancel_delayed_work_sync() is called before i2c_mux_del_adapters() in rtl2832_remove(). While the cancel waits for any running instance of i2c_gate_work to finish, it does not prevent the timer from being rescheduled by a concurrent thread. During probe, the r820t_attach() call attempts I2C transfers through the mux adapter. These transfers go through i2c_mux_master_xfer(), which calls rtl2832_deselect() after the transfer completes, rescheduling i2c_gate_work via schedule_delayed_work(). If this transfer is still in flight when rtl2832_remove() runs, rtl2832_deselect() can reschedule i2c_gate_work after it has been cancelled, causing a use-after-free when kfree(dev) is called. Fix this by calling i2c_mux_del_adapters() before cancel_delayed_work_sync(). Once the mux adapter is unregistered, no new I2C transfers can go through it, so rtl2832_deselect() can no longer reschedule i2c_gate_work. The subsequent cancel_delayed_work_sync() is then guaranteed to be final. Fixes: cddcc40b1b15 ("[media] rtl2832: convert to use an explicit i2c mux c= ore") Cc: stable@vger.kernel.org Reported-by: syzbot+019ced393ab913002b75@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3D019ced393ab913002b75 Signed-off-by: Deepanshu Kartikey --- v3: - Fix missing PATCH v2 prefix in subject line v2: - Fix Signed-off-by email address (lowercase k) - Add Cc: stable@vger.kernel.org for stable backport --- drivers/media/dvb-frontends/rtl2832.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/media/dvb-frontends/rtl2832.c b/drivers/media/dvb-fron= tends/rtl2832.c index d8e1546aea5e..9898f729304a 100644 --- a/drivers/media/dvb-frontends/rtl2832.c +++ b/drivers/media/dvb-frontends/rtl2832.c @@ -1115,10 +1115,10 @@ static void rtl2832_remove(struct i2c_client *clien= t) =20 dev_dbg(&client->dev, "\n"); =20 - cancel_delayed_work_sync(&dev->i2c_gate_work); - i2c_mux_del_adapters(dev->muxc); =20 + cancel_delayed_work_sync(&dev->i2c_gate_work); + regmap_exit(dev->regmap); =20 kfree(dev); --=20 2.43.0