From patchwork Thu Sep 12 14:19:06 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oliver Neukum X-Patchwork-Id: 828633 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 851C22209B for ; Thu, 12 Sep 2024 14:19:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.135.223.131 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726150764; cv=none; b=lmHD70XCcAjqBpyIqOtXPFTh9M3bhZUdpdMWTppCeOzzfB05mmPlu7bCQN4GI7UZL+hC0hRM6MQGEhf+TKcJrS78DzAo37K+vz509xbPej1blbGhMgPonqUQBCWkmZibrSI/A253+cscuL+Om7T7b8rsBxc3+XsB5J0mq6sV3GU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726150764; c=relaxed/simple; bh=E30N8XAuG14BE7RthlFoo+RlpFDcmf+/oXmeiDrHzLU=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=dWP63v/0qAVwsh6JB/PBAAic2uVfdptOxYfas5gwaRITVP6YkYKBX7myvQcsyYaA7M0/Gp4DW3oqKLkZlL6aNCP6wCLaslvwfMe4w0jotl+4/eMq97ZRpWuHXwoeHW037bfsFVwWM1AlRzJnvOcLuh44g3P8wcoRalXW1xCaeuE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b=j6oyyT0r; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b=j6oyyT0r; arc=none smtp.client-ip=195.135.223.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="j6oyyT0r"; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="j6oyyT0r" Received: from imap1.dmz-prg2.suse.org (unknown [10.150.64.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 914331FB7C; Thu, 12 Sep 2024 14:19:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1726150758; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=8b5EVn85IGQz62CFF/P37B2Ccxts7Skxn2LA9b6buQE=; b=j6oyyT0r+IYvVpziPxktzsriGGanQPgkKwC7azuqL6AcBJvc5EH/5i9DEOfpzzowZWd0Mq PTdSkmIEoXpFLlYkN+mltcnkjs03SZwocnDk+gkcnSEXq4GDICze9DSLLmZZaxUHwVx064 j3RADctOpbiH76LG9TKPlKkIKC3TyuM= Authentication-Results: smtp-out2.suse.de; none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1726150758; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=8b5EVn85IGQz62CFF/P37B2Ccxts7Skxn2LA9b6buQE=; b=j6oyyT0r+IYvVpziPxktzsriGGanQPgkKwC7azuqL6AcBJvc5EH/5i9DEOfpzzowZWd0Mq PTdSkmIEoXpFLlYkN+mltcnkjs03SZwocnDk+gkcnSEXq4GDICze9DSLLmZZaxUHwVx064 j3RADctOpbiH76LG9TKPlKkIKC3TyuM= Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 747D313AD8; Thu, 12 Sep 2024 14:19:18 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id jXdLG2b44mbRAQAAD6G6ig (envelope-from ); Thu, 12 Sep 2024 14:19:18 +0000 From: Oliver Neukum To: gregkh@linuxfoundation.org, linux-usb@vger.kernel.org Cc: Oliver Neukum Subject: [PATCH] USB: class: CDC-ACM: fix race between get_serial and set_serial Date: Thu, 12 Sep 2024 16:19:06 +0200 Message-ID: <20240912141916.1044393-1-oneukum@suse.com> X-Mailer: git-send-email 2.45.2 Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Score: -2.80 X-Spamd-Result: default: False [-2.80 / 50.00]; BAYES_HAM(-3.00)[99.99%]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_MISSING_CHARSET(0.50)[]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MIME_TRACE(0.00)[0:+]; TO_DN_SOME(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; DKIM_SIGNED(0.00)[suse.com:s=susede1]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[3]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo]; RCVD_TLS_ALL(0.00)[] X-Spam-Flag: NO X-Spam-Level: TIOCGSERIAL is an ioctl. Thus it must be atomic. It returns two values. Racing with set_serial it can return an inconsistent result. The mutex must be taken. In terms of logic the bug is as old as the driver. In terms of code it goes back to the conversion to the get_serial and set_serial methods. Signed-off-by: Oliver Neukum Fixes: 99f75a1fcd865 ("cdc-acm: switch to ->[sg]et_serial()") --- drivers/usb/class/cdc-acm.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index 0c1b69d944ca..605fea461102 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -962,10 +962,12 @@ static int get_serial_info(struct tty_struct *tty, struct serial_struct *ss) struct acm *acm = tty->driver_data; ss->line = acm->minor; + mutex_lock(&acm->port.mutex); ss->close_delay = jiffies_to_msecs(acm->port.close_delay) / 10; ss->closing_wait = acm->port.closing_wait == ASYNC_CLOSING_WAIT_NONE ? ASYNC_CLOSING_WAIT_NONE : jiffies_to_msecs(acm->port.closing_wait) / 10; + mutex_unlock(&acm->port.mutex); return 0; }