From patchwork Mon Apr 1 19:10:38 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Wetzel X-Patchwork-Id: 13612973 Received: from ns2.wdyn.eu (ns2.wdyn.eu [5.252.227.236]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 712C251C44; Mon, 1 Apr 2024 19:11:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=5.252.227.236 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711998664; cv=none; b=llL3LbC3+HnDpnnrxHrnXwybfutecIUdy+DQlZp1YVlCxHmnK+eq1S9v0tO0LeVSFb/KutQeeDNe7i+RRD87s8Yst+FSJ9N2rWzAAIvH6zFl6tOKrIU/ACRKfhWGYr6qUglxWG6DCGEFI3aFwwYrtR3+TJ6ODYcyO30go9Gnm84= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711998664; c=relaxed/simple; bh=l5AboQBubNlfjPSPGwV6zz3AoCLbpjWMoP+mef5uBv0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pUUM5A84KHYzFqD0HY3NX92V/TfMnYqgHmeVc73MSgey5mVziQZiBwztvygbT3E54au6di++3tNyP/DwmnND85loH8y+5+HJaSGAWkt6IfPJd7WmxZB3Nnsb0D41NBIFsUgvnNbf1IupzmeK/CTU91kpAn9/m91aaywKcCCsxH0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=wetzel-home.de; spf=pass smtp.mailfrom=wetzel-home.de; dkim=pass (1024-bit key) header.d=wetzel-home.de header.i=@wetzel-home.de header.b=poi3KbXQ; arc=none smtp.client-ip=5.252.227.236 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=wetzel-home.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=wetzel-home.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=wetzel-home.de header.i=@wetzel-home.de header.b="poi3KbXQ" From: Alexander Wetzel DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=wetzel-home.de; s=wetzel-home; t=1711998656; bh=l5AboQBubNlfjPSPGwV6zz3AoCLbpjWMoP+mef5uBv0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=poi3KbXQgsHiQr2KDJqeSIxNTyd2cnWiuPiPokZfcHRvP9X0w5IMvYt/TVH/S60+w JgONKIR4R1k/3YQZFFdJTJ39c6VTa8kMQhXXPlnuB9kJnNa9Xw+vpwp5F2oJw7vIsM Z4p/5WjknXHBR7Qxrn/LUdUlxtkknYum/aYm/MyU= To: dgilbert@interlog.com Cc: gregkh@linuxfoundation.org, sachinp@linux.ibm.com, Alexander@wetzel-home.de, bvanassche@acm.org, linux-scsi@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, martin.petersen@oracle.com, stable@vger.kernel.org Subject: [PATCH v3] scsi: sg: Avoid race in error handling & drop bogus warn Date: Mon, 1 Apr 2024 21:10:38 +0200 Message-ID: <20240401191038.18359-1-Alexander@wetzel-home.de> X-Mailer: git-send-email 2.44.0 In-Reply-To: <81266270-42F4-48F9-9139-8F0C3F0A6553@linux.ibm.com> References: <81266270-42F4-48F9-9139-8F0C3F0A6553@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 commit 27f58c04a8f4 ("scsi: sg: Avoid sg device teardown race") introduced an incorrect WARN_ON_ONCE() and missed a sequence where sg_device_destroy() was used after scsi_device_put(). sg_device_destroy() is accessing the parent scsi_device request_queue which will already be set to NULL when the preceding call to scsi_device_put() removed the last reference to the parent scsi_device. Drop the incorrect WARN_ON_ONCE() - allowing more than one concurrent access to the sg device - and make sure sg_device_destroy() is not used after scsi_device_put() in the error handling. Link: https://lore.kernel.org/all/5375B275-D137-4D5F-BE25-6AF8ACAE41EF@linux.ibm.com Fixes: 27f58c04a8f4 ("scsi: sg: Avoid sg device teardown race") Cc: stable@vger.kernel.org Signed-off-by: Alexander Wetzel Tested-by: Sachin Sant Reviewed-by: Bart Van Assche --- Changes compared to V1: fixed commit message Changes compared to V2: Fix use-after free --- drivers/scsi/sg.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index 386981c6976a..baf870a03ecf 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -285,6 +285,7 @@ sg_open(struct inode *inode, struct file *filp) int dev = iminor(inode); int flags = filp->f_flags; struct request_queue *q; + struct scsi_device *device; Sg_device *sdp; Sg_fd *sfp; int retval; @@ -301,11 +302,12 @@ sg_open(struct inode *inode, struct file *filp) /* This driver's module count bumped by fops_get in */ /* Prevent the device driver from vanishing while we sleep */ - retval = scsi_device_get(sdp->device); + device = sdp->device; + retval = scsi_device_get(device); if (retval) goto sg_put; - retval = scsi_autopm_get_device(sdp->device); + retval = scsi_autopm_get_device(device); if (retval) goto sdp_put; @@ -313,7 +315,7 @@ sg_open(struct inode *inode, struct file *filp) * check if O_NONBLOCK. Permits SCSI commands to be issued * during error recovery. Tread carefully. */ if (!((flags & O_NONBLOCK) || - scsi_block_when_processing_errors(sdp->device))) { + scsi_block_when_processing_errors(device))) { retval = -ENXIO; /* we are in error recovery for this device */ goto error_out; @@ -344,7 +346,7 @@ sg_open(struct inode *inode, struct file *filp) if (sdp->open_cnt < 1) { /* no existing opens */ sdp->sgdebug = 0; - q = sdp->device->request_queue; + q = device->request_queue; sdp->sg_tablesize = queue_max_segments(q); } sfp = sg_add_sfp(sdp); @@ -370,10 +372,11 @@ sg_open(struct inode *inode, struct file *filp) error_mutex_locked: mutex_unlock(&sdp->open_rel_lock); error_out: - scsi_autopm_put_device(sdp->device); + scsi_autopm_put_device(device); sdp_put: - scsi_device_put(sdp->device); - goto sg_put; + kref_put(&sdp->d_ref, sg_device_destroy); + scsi_device_put(device); + return retval; } /* Release resources associated with a successful sg_open() @@ -2233,7 +2236,6 @@ sg_remove_sfp_usercontext(struct work_struct *work) "sg_remove_sfp: sfp=0x%p\n", sfp)); kfree(sfp); - WARN_ON_ONCE(kref_read(&sdp->d_ref) != 1); kref_put(&sdp->d_ref, sg_device_destroy); scsi_device_put(device); module_put(THIS_MODULE);