linux-kernel - [PATCH 3.16.y-ckt 110/126] Fix a memory leak in scsi_host_dev

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Message-Id: <1452076655-12851-111-git-send-email-luis.henriques@canonical.com>
Date:	Wed,  6 Jan 2016 10:37:19 +0000
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Bart Van Assche <bart.vanassche@...disk.com>,
	Christoph Hellwig <hch@....de>, Hannes Reinecke <hare@...e.de>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.16.y-ckt 110/126] Fix a memory leak in scsi_host_dev_release()

3.16.7-ckt22 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bart Van Assche <bart.vanassche@...disk.com>

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@...disk.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Reviewed-by: Johannes Thumshirn <jthumshirn@...e.de>
Reviewed-by: Sagi Grimberg <sagig@...lanox.com>
Reviewed-by: Lee Duncan <lduncan@...e.com>
Cc: Christoph Hellwig <hch@....de>
Cc: Hannes Reinecke <hare@...e.de>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 drivers/scsi/hosts.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 3cbb57a8b846..3b43224f7f77 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -308,6 +308,17 @@ 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);
--
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