From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6878F32A3FF; Thu, 16 Jul 2026 13:50:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784209858; cv=none; b=g1j4vwI97nsltGQt5LPDdVuKmAnb8ZR9VB2hIaXNo8UgcgCTxM6s0EXwV2c+XFb4lgJEwh22mf5tt79T6gqKjOr9mk8zI950bj6Yi8UjkbuBaBLGjIKleqd40zMEuEeNt7QONfmM1Ca42PDkEUP+zRBlU5GTKa+FaAP2G1Mx6+o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784209858; c=relaxed/simple; bh=g2VSN5A3LsPa4/vuDZvBBD4H/Nuqc0I5WBRwkMaGebE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=N/YcJTX92RrdLzJEXaXQgzJTWwEoW8KOYljNy5S1H8TANxceS/hCAO9dxP2Jb4uvWaCCCk1SgXvsaV1HjAsEFt1fv+LN2Z1VXVITveU3Vpz70S6Gvl/daVuzTj+kkeOcOZGyj/TN0HTRY/Duyn5a8lBmhuNJbSax0sXV1D/2/mU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=C5dv34t3; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="C5dv34t3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CD1131F000E9; Thu, 16 Jul 2026 13:50:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784209857; bh=0GtZrR3MwMT5OXQXJUGaEWxs0NeYV7KHHk827PYs+Kk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=C5dv34t30NyepePyVeNFhLV/Nqq3BWkWRtLSR7cxzYDKp/+Uv/tDfwXge0C0lV6/H i5ucXAJx9kW6h2+R/MJuR48pxgY3xUc17VpemtqzcmV1wfP3EsK/wPhRpgZVi1u6DS /PlI8Is3+nLC9AxQVIRskfZFgUWbhQ1DrwQLOpjg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Daniel Walker , Johan Hovold Subject: [PATCH 7.1 308/518] USB: ldusb: fix use-after-free on disconnect race Date: Thu, 16 Jul 2026 15:29:36 +0200 Message-ID: <20260716133054.561717811@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260716133047.772246337@linuxfoundation.org> References: <20260716133047.772246337@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Johan Hovold commit 19bdfc7b3c179331eafa423d87e1336f43bbfeb8 upstream. mutex_unlock() may access the mutex structure after releasing the lock and therefore cannot be used to manage lifetime of objects directly (unlike spinlocks and refcounts). [1][2] Use a kref to release the driver data to avoid use-after-free in mutex_unlock() when release() races with disconnect(). [1] a51749ab34d9 ("locking/mutex: Document that mutex_unlock() is non-atomic") [2] 2b9d9e0a9ba0 ("locking/mutex: Clarify that mutex_unlock(), and most other sleeping locks, can still use the lock object after it's unlocked") Fixes: ce0d7d3f575f ("usb: ldusb: ld_usb semaphore to mutex") Cc: stable Cc: Daniel Walker Signed-off-by: Johan Hovold Link: https://patch.msgid.link/20260622152612.116422-4-johan@kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/usb/misc/ldusb.c | 38 ++++++++++++++++++-------------------- 1 file changed, 18 insertions(+), 20 deletions(-) --- a/drivers/usb/misc/ldusb.c +++ b/drivers/usb/misc/ldusb.c @@ -150,6 +150,7 @@ MODULE_PARM_DESC(min_interrupt_out_inter /* Structure to hold all of our device specific stuff */ struct ld_usb { + struct kref kref; struct mutex mutex; /* locks this structure */ struct usb_interface *intf; /* save off the usb interface pointer */ unsigned long disconnected:1; @@ -201,8 +202,10 @@ static void ld_usb_abort_transfers(struc /* * ld_usb_delete */ -static void ld_usb_delete(struct ld_usb *dev) +static void ld_usb_delete(struct kref *kref) { + struct ld_usb *dev = container_of(kref, struct ld_usb, kref); + /* free data structures */ usb_free_urb(dev->interrupt_in_urb); usb_free_urb(dev->interrupt_out_urb); @@ -355,6 +358,8 @@ static int ld_usb_open(struct inode *ino goto unlock_exit; } + kref_get(&dev->kref); + /* save device in the file's private structure */ file->private_data = dev; @@ -381,17 +386,8 @@ static int ld_usb_release(struct inode * mutex_lock(&dev->mutex); - if (dev->open_count != 1) { - retval = -ENODEV; + if (dev->disconnected) goto unlock_exit; - } - if (dev->disconnected) { - /* the device was unplugged before the file was released */ - mutex_unlock(&dev->mutex); - /* unlock here as ld_usb_delete frees dev */ - ld_usb_delete(dev); - goto exit; - } /* wait until write transfer is finished */ if (dev->interrupt_out_busy) @@ -401,7 +397,7 @@ static int ld_usb_release(struct inode * unlock_exit: mutex_unlock(&dev->mutex); - + kref_put(&dev->kref, ld_usb_delete); exit: return retval; } @@ -659,6 +655,8 @@ static int ld_usb_probe(struct usb_inter dev = kzalloc_obj(*dev); if (!dev) goto exit; + + kref_init(&dev->kref); mutex_init(&dev->mutex); spin_lock_init(&dev->rbsl); dev->intf = intf; @@ -740,7 +738,7 @@ exit: return retval; error: - ld_usb_delete(dev); + kref_put(&dev->kref, ld_usb_delete); return retval; } @@ -768,18 +766,18 @@ static void ld_usb_disconnect(struct usb mutex_lock(&dev->mutex); - /* if the device is not opened, then we clean up right now */ - if (!dev->open_count) { - mutex_unlock(&dev->mutex); - ld_usb_delete(dev); - } else { - dev->disconnected = 1; + dev->disconnected = 1; + + if (dev->open_count) { /* wake up pollers */ wake_up_interruptible_all(&dev->read_wait); wake_up_interruptible_all(&dev->write_wait); - mutex_unlock(&dev->mutex); } + mutex_unlock(&dev->mutex); + + kref_put(&dev->kref, ld_usb_delete); + dev_info(&intf->dev, "LD USB Device #%d now disconnected\n", (minor - USB_LD_MINOR_BASE)); }