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 DA7CC3DC4AF for ; Mon, 3 Aug 2026 09:26:10 +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=1785749175; cv=none; b=qfagmMvczKQA3rW+48t/mfUL2nvkJv29ssZkwBnJpvFaGzQRh1Ee7gyb1H0GRnvKmiORYxYIZUVzZ6ZvZu5F/O/GX7JT9YZ6kqmPwn3Mz/XaK6WL31R4UPD/3SMu2XddUs0vSHQrgUSy/3ttA2QKtKt7XcaCkDMEydH1NGerMKY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785749175; c=relaxed/simple; bh=/AHbSs+7RLE/O8H3yWEJA7w7lVuo8uTKOPnrhKw5uLM=; h=From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type:Date; b=S1O9n+TCDauZMHoAevD80ujSGfC8o60DukIE2KxnbFIeHZnNMjt+YrfpgK7VU8zr6r+1wJ67zD2b6I73R66gh6qpHykdTYcEmLz80nXvE6evmqByfSuEGXNAlPWUM47ZzzoXUR28UWTMTCKtem2w08DF4G22MXGuGdv5BovxKnU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=al9pPuYL; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="al9pPuYL" Received: by smtp.kernel.org (Postfix) with UTF8SMTPSA id 70DC91F00A3A; Mon, 3 Aug 2026 09:26:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785749170; bh=a58LqytePNVqZmWaubr/UBreD97Q6dDEXQfqrli1VtE=; h=From:To:Cc:Subject:Date; b=al9pPuYLv7ddhW0MrgY08X6dr/SMumYBAR7Lv8PsjjaHh1EeiXObOUcltbcaHfRSL atuVjhDfgGpvZlSyr7WGbyC7gXE2vbp9XrI6WIJ3WGx+CI2n5DthLlOhwF1BEaUZUE fLZv8Ck31FND5zj2qRJKXndedCauESxp66nmmxUtUQe8YHEsGItyt7wC/F6kN16BTS 8zYw00cLBOMKdrlcmezjqWP/kk1w+UxV5nYaCdlG5joOhinFqJygvG5tKLv8WGllPZ OeDhoeXE6RCKUyG6NHLIhnREg+YM83vSSxwzFGO0707OaAYCV7oF5TqXQn2fxcbEUJ isQ4zT3c/syIw== From: "syzbot" To: syzkaller-upstream-moderation@googlegroups.com Cc: syzbot@lists.linux.dev Subject: [PATCH RFC] usbip: fix use-after-free in event_handler() Message-ID: <330619da-665c-4dd6-ac14-30e8bef174fd@mail.kernel.org> Precedence: bulk X-Mailing-List: syzbot@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Date: Mon, 3 Aug 2026 09:26:10 +0000 (UTC) The event_handler function in drivers/usb/usbip/usbip_event.c is a workqueue item responsible for processing events for a struct usbip_device. During device teardown, usbip_stop_eh() is called to wait for the event handler to finish processing. However, usbip_stop_eh() uses wait_event_interruptible() and ignores its return value. If the process unbinding the driver receives a signal, wait_event_interruptible() returns immediately, causing the teardown process to falsely assume the event handler has finished. The teardown process then proceeds to free the usbip_device memory. Meanwhile, the event_handler workqueue is still running and attempts to access the freed usbip_device, resulting in a KASAN slab-use-after-free crash. BUG: KASAN: slab-use-after-free in __mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline] BUG: KASAN: slab-use-after-free in mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578 Read of size 1 at addr ffff8881145245b0 by task kworker/u8:5/6177 Call Trace: lock_acquire+0x84/0x350 kernel/locking/lockdep.c:5842 __mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline] mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578 event_handler+0x1e3/0x4a0 drivers/usb/usbip/usbip_event.c:73 process_one_work kernel/workqueue.c:3322 [inline] process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 To fix this, change wait_event_interruptible() to wait_event() in usbip_stop_eh(). This ensures that the teardown process strictly waits for the event handler to finish its execution and drop all references to the usbip_device before the memory is freed, preventing the use-after-free. This change is safe from deadlocks because usbip_stop_eh() is never called with locks held that the event_handler would need to acquire. Fixes: bb7871ad99ea ("usbip: event handler as one thread") Assisted-by: Gemini:gemini-3.5-flash Gemini:gemini-3.1-pro-preview syzbot Reported-by: syzbot+f4518ac0a3dd3aafde38@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=f4518ac0a3dd3aafde38 Link: https://syzkaller.appspot.com/ai_job?id=88101c8e-4da9-45de-b879-0549d6fe5649 To: "Greg Kroah-Hartman" To: To: "Shuah Khan" To: "Valentina Manea" To: "Nobuo Iwata" Cc: "Hongren Zheng" Cc: --- diff --git a/drivers/usb/usbip/usbip_event.c b/drivers/usb/usbip/usbip_event.c index 0e00c2d00..81d761891 100644 --- a/drivers/usb/usbip/usbip_event.c +++ b/drivers/usb/usbip/usbip_event.c @@ -115,7 +115,7 @@ void usbip_stop_eh(struct usbip_device *ud) if (pending) usbip_dbg_eh("usbip_eh waiting completion %lx\n", pending); - wait_event_interruptible(ud->eh_waitq, !(ud->event & ~USBIP_EH_BYE)); + wait_event(ud->eh_waitq, !(ud->event & ~USBIP_EH_BYE)); usbip_dbg_eh("usbip_eh has stopped\n"); } EXPORT_SYMBOL_GPL(usbip_stop_eh); base-commit: 075b74841bd0065a3bda3440873c747938e69b68 -- This is an AI-generated patch subject to moderation. 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