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([2405:201:682f:383f:1a11:fc4d:ef1d:6578]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-14d088e5b9asm2445733c88.9.2026.09.30.01.35.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Sep 2026 01:36:00 -0700 (PDT) From: Deepanshu Kartikey To: sean@mess.org, mchehab@kernel.org Cc: jarod@redhat.com, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Deepanshu Kartikey , syzbot+9bfac891bdd42eb708fc@syzkaller.appspotmail.com Subject: [PATCH] media: imon: fix use-after-free in display_close via dev_dbg Date: Wed, 30 Sep 2026 14:05:51 +0530 Message-ID: <20260930083551.15905-1-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: 8bit ictx->dev is a raw pointer to the usb_interface's embedded device. On disconnect, usb_disconnect() can drop the last reference on the interface and free it while a userspace fd for /dev/lcd0 is still open. When that fd is later closed, display_close() dereferences the now-freed ictx->dev via dev_dbg(), causing a use-after-free. Remove the dev_dbg() calls that dereference ictx->dev in display_close() and free_imon_context(), rather than taking a reference on the device. Fixes: 21677cfc562a ("V4L/DVB: ir-core: add imon driver") Reported-by: syzbot+9bfac891bdd42eb708fc@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=9bfac891bdd42eb708fc Link: https://lore.kernel.org/all/20260918054851.26083-1-kartikey406@gmail.com/T/ [v1] Link: https://lore.kernel.org/all/20260928121230.35359-1-kartikey406@gmail.com/T/ [v2] Signed-off-by: Deepanshu Kartikey --- v3: - Drop the dev_dbg() calls entirely instead of pinning the device with get_device()/put_device(), per Sean Young. v2: - Remove the dev_dbg() in free_imon_context(), as suggested by Sean Young. --- drivers/media/rc/imon.c | 5 ----- 1 file changed, 5 deletions(-) diff --git a/drivers/media/rc/imon.c b/drivers/media/rc/imon.c index 049a73b5f882..e54b588ff61c 100644 --- a/drivers/media/rc/imon.c +++ b/drivers/media/rc/imon.c @@ -492,16 +492,12 @@ MODULE_PARM_DESC(pad_thresh, "Threshold at which a pad push registers as an arro static void free_imon_context(struct imon_context *ictx) { - struct device *dev = ictx->dev; - usb_free_urb(ictx->tx_urb); WARN_ON(ictx->dev_present_intf0); usb_free_urb(ictx->rx_urb_intf0); WARN_ON(ictx->dev_present_intf1); usb_free_urb(ictx->rx_urb_intf1); kfree_rcu(ictx, rcu); - - dev_dbg(dev, "%s: iMON context freed\n", __func__); } /* @@ -577,7 +573,6 @@ static int display_close(struct inode *inode, struct file *file) retval = -EIO; } else { ictx->display_isopen = false; - dev_dbg(ictx->dev, "display port closed\n"); } mutex_unlock(&ictx->lock); -- 2.43.0