[3.13.y-ckt stable] Patch "Fix a memory leak in scsi_host_dev_release()" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    Fix a memory leak in scsi_host_dev_release()

to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11-ckt32.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From e8bfcc58275e0a7ef6850175d85578e309b8f54c Mon Sep 17 00:00:00 2001
From: Bart Van Assche <bart.vanassche at sandisk.com>
Date: Wed, 18 Nov 2015 14:56:36 -0800
Subject: Fix a memory leak in scsi_host_dev_release()

commit b49493f99690c8eaacfbc635bafaad629ea2c036 upstream.

Avoid that kmemleak reports the following memory leak if a
SCSI LLD calls scsi_host_alloc() and scsi_host_put() but neither
scsi_host_add() nor scsi_host_remove(). The following shell
command triggers that scenario:

for ((i=0; i<2; i++)); do
  srp_daemon -oac |
  while read line; do
    echo $line >/sys/class/infiniband_srp/srp-mlx4_0-1/add_target
  done
done

unreferenced object 0xffff88021b24a220 (size 8):
  comm "srp_daemon", pid 56421, jiffies 4295006762 (age 4240.750s)
  hex dump (first 8 bytes):
    68 6f 73 74 35 38 00 a5                          host58..
  backtrace:
    [<ffffffff8151014a>] kmemleak_alloc+0x7a/0xc0
    [<ffffffff81165c1e>] __kmalloc_track_caller+0xfe/0x160
    [<ffffffff81260d2b>] kvasprintf+0x5b/0x90
    [<ffffffff81260e2d>] kvasprintf_const+0x8d/0xb0
    [<ffffffff81254b0c>] kobject_set_name_vargs+0x3c/0xa0
    [<ffffffff81337e3c>] dev_set_name+0x3c/0x40
    [<ffffffff81355757>] scsi_host_alloc+0x327/0x4b0
    [<ffffffffa03edc8e>] srp_create_target+0x4e/0x8a0 [ib_srp]
    [<ffffffff8133778b>] dev_attr_store+0x1b/0x20
    [<ffffffff811f27fa>] sysfs_kf_write+0x4a/0x60
    [<ffffffff811f1e8e>] kernfs_fop_write+0x14e/0x180
    [<ffffffff81176eef>] __vfs_write+0x2f/0xf0
    [<ffffffff811771e4>] vfs_write+0xa4/0x100
    [<ffffffff81177c64>] SyS_write+0x54/0xc0
    [<ffffffff8151b257>] entry_SYSCALL_64_fastpath+0x12/0x6f

Signed-off-by: Bart Van Assche <bart.vanassche at sandisk.com>
Reviewed-by: Christoph Hellwig <hch at lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn at suse.de>
Reviewed-by: Sagi Grimberg <sagig at mellanox.com>
Reviewed-by: Lee Duncan <lduncan at suse.com>
Cc: Christoph Hellwig <hch at lst.de>
Cc: Hannes Reinecke <hare at suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen at oracle.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/scsi/hosts.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index f2c5005..3b7d405 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -305,6 +305,17 @@ static void scsi_host_dev_release(struct device *dev)
 		kfree(queuedata);
 	}

+	if (shost->shost_state == SHOST_CREATED) {
+		/*
+		 * Free the shost_dev device name here if scsi_host_alloc()
+		 * and scsi_host_put() have been called but neither
+		 * scsi_host_add() nor scsi_host_remove() has been called.
+		 * This avoids that the memory allocated for the shost_dev
+		 * name is leaked.
+		 */
+		kfree(dev_name(&shost->shost_dev));
+	}
+
 	scsi_destroy_command_freelist(shost);
 	if (shost->bqt)
 		blk_free_tags(shost->bqt);
--
1.9.1