This is a note to let you know that I've just added the patch titled

pktcdvd: Fix a recently introduced NULL pointer dereference

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: pktcdvd-fix-a-recently-introduced-null-pointer-dereference.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 882d4171a8950646413b1a3cbe0e4a6a612fe82e Mon Sep 17 00:00:00 2001

From: Bart Van Assche bart.vanassche@wdc.com Date: Tue, 2 Jan 2018 11:39:48 -0800 Subject: pktcdvd: Fix a recently introduced NULL pointer dereference

From: Bart Van Assche bart.vanassche@wdc.com

commit 882d4171a8950646413b1a3cbe0e4a6a612fe82e upstream.

Call bdev_get_queue(bdev) after bdev->bd_disk has been initialized instead of just before that pointer has been initialized. This patch avoids that the following command

pktsetup 1 /dev/sr0

triggers the following kernel crash:

BUG: unable to handle kernel NULL pointer dereference at 0000000000000548 IP: pkt_setup_dev+0x2db/0x670 [pktcdvd] CPU: 2 PID: 724 Comm: pktsetup Not tainted 4.15.0-rc4-dbg+ #1 Call Trace: pkt_ctl_ioctl+0xce/0x1c0 [pktcdvd] do_vfs_ioctl+0x8e/0x670 SyS_ioctl+0x3c/0x70 entry_SYSCALL_64_fastpath+0x23/0x9a

Reported-by: Maciej S. Szmigiero mail@maciej.szmigiero.name Fixes: commit ca18d6f769d2 ("block: Make most scsi_req_init() calls implicit") Signed-off-by: Bart Van Assche bart.vanassche@wdc.com Tested-by: Maciej S. Szmigiero mail@maciej.szmigiero.name Cc: Maciej S. Szmigiero mail@maciej.szmigiero.name Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- drivers/block/pktcdvd.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/block/pktcdvd.c +++ b/drivers/block/pktcdvd.c @@ -2579,14 +2579,14 @@ static int pkt_new_dev(struct pktcdvd_de bdev = bdget(dev); if (!bdev) return -ENOMEM; + ret = blkdev_get(bdev, FMODE_READ | FMODE_NDELAY, NULL); + if (ret) + return ret; if (!blk_queue_scsi_passthrough(bdev_get_queue(bdev))) { WARN_ONCE(true, "Attempt to register a non-SCSI queue\n"); - bdput(bdev); + blkdev_put(bdev, FMODE_READ | FMODE_NDELAY); return -EINVAL; } - ret = blkdev_get(bdev, FMODE_READ | FMODE_NDELAY, NULL); - if (ret) - return ret;

/* This is safe, since we have a reference from open(). */ __module_get(THIS_MODULE);

Patches currently in stable-queue which might be from bart.vanassche@wdc.com are

queue-4.14/pktcdvd-fix-pkt_setup_dev-error-path.patch queue-4.14/pktcdvd-fix-a-recently-introduced-null-pointer-dereference.patch