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(2.133.25.254.dynamic.telecom.kz. [2.133.25.254]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-36e4ecc7a52sm8910469f8f.103.2024.08.12.21.04.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 12 Aug 2024 21:04:53 -0700 (PDT) From: Sabyrzhan Tasbolatov To: eli.billauer@gmail.com, arnd@arndb.de, gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, Sabyrzhan Tasbolatov , syzbot+e528c9aad0fb5383ec83@syzkaller.appspotmail.com Subject: [PATCH] drivers/xillybus: fix deadlock upon cleanup_dev Date: Tue, 13 Aug 2024 09:04:25 +0500 Message-Id: <20240813040425.187418-1-snovitoll@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" syzbot found an issue [1] when cleanup_dev() is called twice, causing deadlock. It is called in xillyusb_probe() in the end of wakeup_all(): INIT_WORK(&xdev->wakeup_workitem, wakeup_all); then on "goto fail" path it's called again, where it's deadlocked in destroy_workqueue(xdev->workq) due to first call's work_completion. Also the deadlock prevents UAF as cleanup_dev frees struct xillyusb_dev. It should be also the cause of previous syzbot report which was fixed in commit 0d151a103775 ("Bluetooth: hci_core: cancel all works upon hci_unregister_dev()"). [1] WARNING: possible recursive locking detected 6.11.0-rc2-syzkaller-00004-gb446a2dae984 #0 Not tainted Reported-by: syzbot+e528c9aad0fb5383ec83@syzkaller.appspotmail.com -------------------------------------------- kworker/0:1H/58 is trying to acquire lock: ((wq_completion)xillyusb){+.+.}-{0:0}, ((wq_completion)xillyusb){+.+.}-{0:0}, but task is already holding lock: ((wq_completion)xillyusb){+.+.}-{0:0}, ((wq_completion)xillyusb){+.+.}-{0:0}, other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock((wq_completion)xillyusb); lock((wq_completion)xillyusb); *** DEADLOCK *** May be due to missing lock nesting notation 2 locks held by kworker/0:1H/58: #0: ((wq_completion)xillyusb){+.+.}-{0:0}, #0: ((wq_completion)xillyusb){+.+.}-{0:0}, #1: ((work_completion)(&xdev->wakeup_workitem)){+.+.}-{0:0}, #1: ((work_completion)(&xdev->wakeup_workitem)){+.+.}-{0:0}, Signed-off-by: Sabyrzhan Tasbolatov Reported-by: syzbot+e528c9aad0fb5383ec83@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3De528c9aad0fb5383ec83 Fixes: a53d1202aef1 ("char: xillybus: Add driver for XillyUSB (Xillybus var= iant for USB)") --- drivers/char/xillybus/xillyusb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/char/xillybus/xillyusb.c b/drivers/char/xillybus/xilly= usb.c index 5a5afa14ca8c..099fe681aed5 100644 --- a/drivers/char/xillybus/xillyusb.c +++ b/drivers/char/xillybus/xillyusb.c @@ -2151,6 +2151,7 @@ static int xillyusb_probe(struct usb_interface *inter= face, if (!xdev->workq) { dev_err(&interface->dev, "Failed to allocate work queue\n"); rc =3D -ENOMEM; + kref_put(&xdev->kref, cleanup_dev); goto fail; } =20 @@ -2174,7 +2175,6 @@ static int xillyusb_probe(struct usb_interface *inter= face, =20 fail: usb_set_intfdata(interface, NULL); - kref_put(&xdev->kref, cleanup_dev); return rc; } =20 --=20 2.34.1