From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 14AC31DDE9; Thu, 30 Jan 2025 14:17:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738246671; cv=none; b=pXKN9q0KpSseVgnW6T3Nw6XoVAyz5Qo1kKpOFVZKcBr2KnYQlRLg/Z9RbZe2ThrXBUfPv0eeDsdlnymPfJkB4rFY3i8/xxhZGuSo3a19mPYAD37mJp89fjTCy19/wLRbx9AYEqANBSSNN86wpBbIOYxI5M/11E1jKm2+Ll0n7zM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738246671; c=relaxed/simple; bh=Zsbl8CpHyqtDY7xePEk4xYEESeTY0p6qayuk2lnCD2A=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XhFXZgzOgc6p/P4S83IENku2qKrZQUyo2okVaKYjhCvexRSTrGp7XeepBF/seR0W6QUw6Sfxln9tO0KmrAcQofKkAmjWlrhuF0bDk4adyO+1qD2X4E7O+uwojHoC75HPuBR8rtnLph37Zvm6qhE5O9pIHtXips1pHaGho+/Jv9Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=M4Lxl8hG; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="M4Lxl8hG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 931D4C4CED2; Thu, 30 Jan 2025 14:17:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1738246671; bh=Zsbl8CpHyqtDY7xePEk4xYEESeTY0p6qayuk2lnCD2A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=M4Lxl8hGty4CGcxl6kgh48IUbxp1n3yFEGqEP1+jl1aNwSs5GUAvDAK2rx+GW5A26 XnR2DPvwBSotJT0ybh1rx2hoOx8YSvrUpFQkLrv5kK1nRCZ5f7fKbAHRlG1bxsZfdV OZ7jWRIbUUPI2u5Qi4UKNEocNbDBpzyWqdqDHHa8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Akash M Subject: [PATCH 5.4 28/91] usb: gadget: f_fs: Remove WARN_ON in functionfs_bind Date: Thu, 30 Jan 2025 15:00:47 +0100 Message-ID: <20250130140134.798667586@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250130140133.662535583@linuxfoundation.org> References: <20250130140133.662535583@linuxfoundation.org> User-Agent: quilt/0.68 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 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Akash M commit dfc51e48bca475bbee984e90f33fdc537ce09699 upstream. This commit addresses an issue related to below kernel panic where panic_on_warn is enabled. It is caused by the unnecessary use of WARN_ON in functionsfs_bind, which easily leads to the following scenarios. 1.adb_write in adbd 2. UDC write via configfs ================= ===================== ->usb_ffs_open_thread() ->UDC write ->open_functionfs() ->configfs_write_iter() ->adb_open() ->gadget_dev_desc_UDC_store() ->adb_write() ->usb_gadget_register_driver_owner ->driver_register() ->StartMonitor() ->bus_add_driver() ->adb_read() ->gadget_bind_driver() ->configfs_composite_bind() ->usb_add_function() ->open_functionfs() ->ffs_func_bind() ->adb_open() ->functionfs_bind() state !=FFS_ACTIVE> The adb_open, adb_read, and adb_write operations are invoked from the daemon, but trying to bind the function is a process that is invoked by UDC write through configfs, which opens up the possibility of a race condition between the two paths. In this race scenario, the kernel panic occurs due to the WARN_ON from functionfs_bind when panic_on_warn is enabled. This commit fixes the kernel panic by removing the unnecessary WARN_ON. Kernel panic - not syncing: kernel: panic_on_warn set ... [ 14.542395] Call trace: [ 14.542464] ffs_func_bind+0x1c8/0x14a8 [ 14.542468] usb_add_function+0xcc/0x1f0 [ 14.542473] configfs_composite_bind+0x468/0x588 [ 14.542478] gadget_bind_driver+0x108/0x27c [ 14.542483] really_probe+0x190/0x374 [ 14.542488] __driver_probe_device+0xa0/0x12c [ 14.542492] driver_probe_device+0x3c/0x220 [ 14.542498] __driver_attach+0x11c/0x1fc [ 14.542502] bus_for_each_dev+0x104/0x160 [ 14.542506] driver_attach+0x24/0x34 [ 14.542510] bus_add_driver+0x154/0x270 [ 14.542514] driver_register+0x68/0x104 [ 14.542518] usb_gadget_register_driver_owner+0x48/0xf4 [ 14.542523] gadget_dev_desc_UDC_store+0xf8/0x144 [ 14.542526] configfs_write_iter+0xf0/0x138 Fixes: ddf8abd25994 ("USB: f_fs: the FunctionFS driver") Cc: stable Signed-off-by: Akash M Link: https://lore.kernel.org/r/20241219125221.1679-1-akash.m5@samsung.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/f_fs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -1875,7 +1875,7 @@ static int functionfs_bind(struct ffs_da ENTER(); - if (WARN_ON(ffs->state != FFS_ACTIVE + if ((ffs->state != FFS_ACTIVE || test_and_set_bit(FFS_FL_BOUND, &ffs->flags))) return -EBADFD;