From patchwork Wed Oct 2 13:21:41 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oliver Neukum X-Patchwork-Id: 832695 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 91D3B1CF28B; Wed, 2 Oct 2024 13:22:05 +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=1727875327; cv=none; b=biJJJw29FtpeyhjPxoQLdTT3wYITrrfh7pa5n4y4eaO+QrhG+1LSudEWl9TrRPnmMwVtBVx3StAgxVsjXF2VIiQrxjWvgOnmpjzsGqbt2DEtxRVlM+fQ9tm1insw6CIbN0UW8EmU/XFUpqVnJHf6Z9B8VRadf1oTtwp9NF8kWR4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727875327; c=relaxed/simple; bh=lvQtIkNhcOBFVU03ImrmL497/i4KYu1ckOuim9XxgVU=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=jqUN18TWjj5LYODY4VP52UNBe/IGdCKXW9cWB7hpXwVsMD+vUGwNAg7bl7g4Gj/BdiG0n2qBuNWgszn/PQG1x7V4JoU2nW1Bhi5K64bagXa0Fek/i8/hHsuH/cfAXo/jIvYNQNHJ3a1AWdQP/dID1ors8O6TXa085pM1YJsmk2c= 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=KC3mRczq; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b=KC3mRczq; 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="KC3mRczq"; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="KC3mRczq" Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (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 BE2731FD5F; Wed, 2 Oct 2024 13:22:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1727875323; 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=HGMmi+18cEyjZ0iT69AoFnPGR02WVVhK+v9hzQ2Rpbc=; b=KC3mRczqxnYFGeCFKg37+vseLzilg0AHhrDqlDaYsmzWl/ZzkRitHKc8XWlPYzkhO2WgB4 z2mf7hITAq9TSLHAHVEzOwlK8jJkgM56Xdhzg0koRPl+hzNhtEuNxhN487LjNZ19654zMD v9lyp/ormLrzW8766IRgVHhoBvGDWwo= Authentication-Results: smtp-out2.suse.de; dkim=pass header.d=suse.com header.s=susede1 header.b=KC3mRczq DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1727875323; 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=HGMmi+18cEyjZ0iT69AoFnPGR02WVVhK+v9hzQ2Rpbc=; b=KC3mRczqxnYFGeCFKg37+vseLzilg0AHhrDqlDaYsmzWl/ZzkRitHKc8XWlPYzkhO2WgB4 z2mf7hITAq9TSLHAHVEzOwlK8jJkgM56Xdhzg0koRPl+hzNhtEuNxhN487LjNZ19654zMD v9lyp/ormLrzW8766IRgVHhoBvGDWwo= 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 91CE713A6E; Wed, 2 Oct 2024 13:22:03 +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 5a1lIvtI/WaxGwAAD6G6ig (envelope-from ); Wed, 02 Oct 2024 13:22:03 +0000 From: Oliver Neukum To: keithp@keithp.com, gregkh@linuxfoundation.org, stable@vger.kernel.org, linux-usb@vger.kernel.org Cc: Oliver Neukum , syzbot+422188bce66e76020e55@syzkaller.appspotmail.com Subject: [PATCH] USB: chaoskey: fail open after removal Date: Wed, 2 Oct 2024 15:21:41 +0200 Message-ID: <20241002132201.552578-1-oneukum@suse.com> X-Mailer: git-send-email 2.46.1 Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Rspamd-Queue-Id: BE2731FD5F X-Spam-Score: -1.51 X-Rspamd-Action: no action X-Spamd-Result: default: False [-1.51 / 50.00]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_MISSING_CHARSET(0.50)[]; NEURAL_HAM_SHORT(-0.20)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.com:s=susede1]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; TO_DN_SOME(0.00)[]; DKIM_SIGNED(0.00)[suse.com:s=susede1]; MIME_TRACE(0.00)[0:+]; FUZZY_BLOCKED(0.00)[rspamd.com]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; ARC_NA(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; TAGGED_RCPT(0.00)[422188bce66e76020e55]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; RCVD_COUNT_TWO(0.00)[2]; DKIM_TRACE(0.00)[suse.com:+]; FROM_EQ_ENVFROM(0.00)[]; RCVD_TLS_ALL(0.00)[]; RCPT_COUNT_FIVE(0.00)[6]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:dkim, suse.com:mid, suse.com:email, imap1.dmz-prg2.suse.org:rdns, imap1.dmz-prg2.suse.org:helo] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Spam-Flag: NO X-Spam-Level: chaoskey_open() takes the lock only to increase the counter of openings. That means that the mutual exclusion with chaoskey_disconnect() cannot prevent an increase of the counter and chaoskey_open() returning a success. If that race is hit, chaoskey_disconnect() will happily free all resources associated with the device after it has dropped the lock, as it has read the counter as zero. To prevent this race chaoskey_open() has to check the presence of the device under the lock. However, the current per device lock cannot be used, because it is a part of the data structure to be freed. Hence an additional global mutex is needed. The issue is as old as the driver. Signed-off-by: Oliver Neukum Reported-by: syzbot+422188bce66e76020e55@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=422188bce66e76020e55 Fixes: 66e3e591891da ("usb: Add driver for Altus Metrum ChaosKey device (v2)") --- drivers/usb/misc/chaoskey.c | 35 ++++++++++++++++++++++++----------- 1 file changed, 24 insertions(+), 11 deletions(-) diff --git a/drivers/usb/misc/chaoskey.c b/drivers/usb/misc/chaoskey.c index 6fb5140e29b9..e8b63df5f975 100644 --- a/drivers/usb/misc/chaoskey.c +++ b/drivers/usb/misc/chaoskey.c @@ -27,6 +27,8 @@ static struct usb_class_driver chaoskey_class; static int chaoskey_rng_read(struct hwrng *rng, void *data, size_t max, bool wait); +static DEFINE_MUTEX(chaoskey_list_lock); + #define usb_dbg(usb_if, format, arg...) \ dev_dbg(&(usb_if)->dev, format, ## arg) @@ -230,6 +232,7 @@ static void chaoskey_disconnect(struct usb_interface *interface) if (dev->hwrng_registered) hwrng_unregister(&dev->hwrng); + mutex_lock(&chaoskey_list_lock); usb_deregister_dev(interface, &chaoskey_class); usb_set_intfdata(interface, NULL); @@ -244,6 +247,7 @@ static void chaoskey_disconnect(struct usb_interface *interface) } else mutex_unlock(&dev->lock); + mutex_unlock(&chaoskey_list_lock); usb_dbg(interface, "disconnect done"); } @@ -251,6 +255,7 @@ static int chaoskey_open(struct inode *inode, struct file *file) { struct chaoskey *dev; struct usb_interface *interface; + int rv = 0; /* get the interface from minor number and driver information */ interface = usb_find_interface(&chaoskey_driver, iminor(inode)); @@ -266,18 +271,23 @@ static int chaoskey_open(struct inode *inode, struct file *file) } file->private_data = dev; + mutex_lock(&chaoskey_list_lock); mutex_lock(&dev->lock); - ++dev->open; + if (dev->present) + ++dev->open; + else + rv = -ENODEV; mutex_unlock(&dev->lock); + mutex_unlock(&chaoskey_list_lock); - usb_dbg(interface, "open success"); - return 0; + return rv; } static int chaoskey_release(struct inode *inode, struct file *file) { struct chaoskey *dev = file->private_data; struct usb_interface *interface; + int rv = 0; if (dev == NULL) return -ENODEV; @@ -286,14 +296,15 @@ static int chaoskey_release(struct inode *inode, struct file *file) usb_dbg(interface, "release"); + mutex_lock(&chaoskey_list_lock); mutex_lock(&dev->lock); usb_dbg(interface, "open count at release is %d", dev->open); if (dev->open <= 0) { usb_dbg(interface, "invalid open count (%d)", dev->open); - mutex_unlock(&dev->lock); - return -ENODEV; + rv = -ENODEV; + goto bail; } --dev->open; @@ -302,13 +313,15 @@ static int chaoskey_release(struct inode *inode, struct file *file) if (dev->open == 0) { mutex_unlock(&dev->lock); chaoskey_free(dev); - } else - mutex_unlock(&dev->lock); - } else - mutex_unlock(&dev->lock); - + goto destruction; + } + } +bail: + mutex_unlock(&dev->lock); +destruction: + mutex_lock(&chaoskey_list_lock); usb_dbg(interface, "release success"); - return 0; + return rv; } static void chaos_read_callback(struct urb *urb)