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 9BD2C143C6E; Wed, 3 Jul 2024 11:20:35 +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=1720005635; cv=none; b=LWHlzqcWvAfppfvW2XbOZ3cofr+Na4h296xVq7KfLJvH8Ilsivipszah5RoPukfTB9ZQSHnc518uW8GRo1GB0bk4eFg76smPV4LGLQNg6PCaSxUfiSonXxJhPAcvYd+WfT16mzIxL1CSQwg0U7v+ncfH0pDXJy1pQWo0KA1Kw+M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720005635; c=relaxed/simple; bh=wt1oeOBo7P3Xv8dhbBevBp49jj2BCzpPQLbz5J39VBU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GUcgjSTqgzHn50hzuT+xuz9k5UROB6pBf22OjsCRbirt1SNpdVCFP57OIOccGnLt0cDrhKSWzaP64vZjs2xDnt9DeRwfaGiKEIc0PW8fF0qKTzuMwC7te+Q+IrRVGuINdG72m+hfMBEDSGm8e6yYRzrIB1BARfdaZ1Edqenewow= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=AnrXECEd; 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="AnrXECEd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0EC14C2BD10; Wed, 3 Jul 2024 11:20:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1720005635; bh=wt1oeOBo7P3Xv8dhbBevBp49jj2BCzpPQLbz5J39VBU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AnrXECEdBWWLkJJPV0hhjj0C4//huG/0surxDTgOG8+TIdWfgGLdVgB5B8jRmmZAO OlcRC4sXG71gMpIv76399QH3H4nVkhryNB6u0DanuxcNLgOfbzq26ALTAnJlGJwM2p fJLQ56Cr9mO4sfpx+5MqIrvKso3RcYTf3H/SghAY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , syzbot+ffa8143439596313a85a@syzkaller.appspotmail.com, Ashish Sangwan , Namjae Jeon , Dirk Behme Subject: [PATCH 5.15 114/356] drivers: core: synchronize really_probe() and dev_uevent() Date: Wed, 3 Jul 2024 12:37:30 +0200 Message-ID: <20240703102917.410963846@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240703102913.093882413@linuxfoundation.org> References: <20240703102913.093882413@linuxfoundation.org> User-Agent: quilt/0.67 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 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dirk Behme commit c0a40097f0bc81deafc15f9195d1fb54595cd6d0 upstream. Synchronize the dev->driver usage in really_probe() and dev_uevent(). These can run in different threads, what can result in the following race condition for dev->driver uninitialization: Thread #1: ========== really_probe() { ... probe_failed: ... device_unbind_cleanup(dev) { ... dev->driver = NULL; // <= Failed probe sets dev->driver to NULL ... } ... } Thread #2: ========== dev_uevent() { ... if (dev->driver) // If dev->driver is NULLed from really_probe() from here on, // after above check, the system crashes add_uevent_var(env, "DRIVER=%s", dev->driver->name); ... } really_probe() holds the lock, already. So nothing needs to be done there. dev_uevent() is called with lock held, often, too. But not always. What implies that we can't add any locking in dev_uevent() itself. So fix this race by adding the lock to the non-protected path. This is the path where above race is observed: dev_uevent+0x235/0x380 uevent_show+0x10c/0x1f0 <= Add lock here dev_attr_show+0x3a/0xa0 sysfs_kf_seq_show+0x17c/0x250 kernfs_seq_show+0x7c/0x90 seq_read_iter+0x2d7/0x940 kernfs_fop_read_iter+0xc6/0x310 vfs_read+0x5bc/0x6b0 ksys_read+0xeb/0x1b0 __x64_sys_read+0x42/0x50 x64_sys_call+0x27ad/0x2d30 do_syscall_64+0xcd/0x1d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f Similar cases are reported by syzkaller in https://syzkaller.appspot.com/bug?extid=ffa8143439596313a85a But these are regarding the *initialization* of dev->driver dev->driver = drv; As this switches dev->driver to non-NULL these reports can be considered to be false-positives (which should be "fixed" by this commit, as well, though). The same issue was reported and tried to be fixed back in 2015 in https://lore.kernel.org/lkml/1421259054-2574-1-git-send-email-a.sangwan@samsung.com/ already. Fixes: 239378f16aa1 ("Driver core: add uevent vars for devices of a class") Cc: stable Cc: syzbot+ffa8143439596313a85a@syzkaller.appspotmail.com Cc: Ashish Sangwan Cc: Namjae Jeon Signed-off-by: Dirk Behme Link: https://lore.kernel.org/r/20240513050634.3964461-1-dirk.behme@de.bosch.com Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -2404,8 +2404,11 @@ static ssize_t uevent_show(struct device if (!env) return -ENOMEM; + /* Synchronize with really_probe() */ + device_lock(dev); /* let the kset specific function add its keys */ retval = kset->uevent_ops->uevent(kset, &dev->kobj, env); + device_unlock(dev); if (retval) goto out;