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: [PATCH] pktcdvd: Fix a recently introduced NULL pointer dereference
Git-commit: 882d4171a8950646413b1a3cbe0e4a6a612fe82e
Patch-mainline: v4.16-rc1
References: bsc#1099918
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>
Cc: <stable@vger.kernel.org> # v4.13
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Coly Li <colyli@suse.de>
---
drivers/block/pktcdvd.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index 2659b2534073..531a0915066b 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -2579,14 +2579,14 @@ static int pkt_new_dev(struct pktcdvd_device *pd, dev_t dev)
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);
--
2.17.1