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Wed, 23 Sep 2026 22:07:19 -0700 (PDT) Received: from archlinux ([188.163.27.108]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48868889926sm15720202f8f.36.2026.09.23.22.07.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Sep 2026 22:07:18 -0700 (PDT) From: Matvey Valigura To: Greg Kroah-Hartman , Chas Williams <3chas3@gmail.com>, Duncan Sands Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, syzbot+9ca2c9f85bd8b5e46516@syzkaller.appspotmail.com, Matvey Valigura , stable@vger.kernel.org Subject: [PATCH] usb: atm: use request_firmware_direct() for firmware probing Date: Thu, 24 Sep 2026 08:06:54 +0300 Message-ID: <20260924050654.15347-1-valigurasm@gmail.com> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When disconnecting a device while firmware is not present on the system, usbatm_usb_disconnect() waits for the heavy_init thread to finish: wait_for_completion(&instance->thread_exited); If CONFIG_FW_LOADER_USER_HELPER_FALLBACK is enabled, missing firmware causes request_firmware() to fall back to sysfs/udevd. This creates a circular dependency during disconnect: 1. usb_disconnect() holds device_lock(&udev->dev). 2. usbatm_usb_disconnect() waits for instance->thread to exit. 3. instance->thread waits for request_firmware() sysfs fallback. 4. udevd receives the firmware uevent and attempts to read sysfs attributes (e.g. serial), blocking on device_lock(&udev->dev). Furthermore, the fallback wait uses wait_for_completion_killable_timeout(), which ignores the non-fatal SIGTERM signal sent by usbatm_usb_disconnect(). Because speedtch and cxacru probe multiple candidate firmware files sequentially, each file stalls for the 60-second fallback timeout, triggering hung task timeouts (>120s) reported by syzbot. Switch to request_firmware_direct() to probe firmware files directly from the filesystem without falling back to user-mode helper. Reported-by: syzbot+9ca2c9f85bd8b5e46516@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=9ca2c9f85bd8b5e46516 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Matvey Valigura --- drivers/usb/atm/cxacru.c | 2 +- drivers/usb/atm/speedtch.c | 6 +++--- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/usb/atm/cxacru.c b/drivers/usb/atm/cxacru.c index 636f7886f..7d1944487 100644 --- a/drivers/usb/atm/cxacru.c +++ b/drivers/usb/atm/cxacru.c @@ -993,7 +993,7 @@ static int cxacru_find_firmware(struct cxacru_data *instance, sprintf(buf, "cxacru-%s.bin", phase); usb_dbg(usbatm, "cxacru_find_firmware: looking for %s\n", buf); - if (request_firmware(fw_p, buf, dev)) { + if (request_firmware_direct(fw_p, buf, dev)) { usb_dbg(usbatm, "no stage %s firmware found\n", phase); return -ENOENT; } diff --git a/drivers/usb/atm/speedtch.c b/drivers/usb/atm/speedtch.c index 9d28c652b..c82db2f7a 100644 --- a/drivers/usb/atm/speedtch.c +++ b/drivers/usb/atm/speedtch.c @@ -357,15 +357,15 @@ static int speedtch_find_firmware(struct usbatm_data *usbatm, struct usb_interfa sprintf(buf, "speedtch-%d.bin.%x.%02x", phase, major_revision, minor_revision); usb_dbg(usbatm, "%s: looking for %s\n", __func__, buf); - if (request_firmware(fw_p, buf, dev)) { + if (request_firmware_direct(fw_p, buf, dev)) { sprintf(buf, "speedtch-%d.bin.%x", phase, major_revision); usb_dbg(usbatm, "%s: looking for %s\n", __func__, buf); - if (request_firmware(fw_p, buf, dev)) { + if (request_firmware_direct(fw_p, buf, dev)) { sprintf(buf, "speedtch-%d.bin", phase); usb_dbg(usbatm, "%s: looking for %s\n", __func__, buf); - if (request_firmware(fw_p, buf, dev)) { + if (request_firmware_direct(fw_p, buf, dev)) { usb_err(usbatm, "%s: no stage %d firmware found!\n", __func__, phase); return -ENOENT; } -- 2.55.0