linux-kernel - [patch] tcm_loop: use after free on error

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Date:	Wed, 2 Mar 2016 13:09:41 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	"Nicholas A. Bellinger" <nab@...ux-iscsi.org>,
	Christoph Hellwig <hch@....de>
Cc:	Hannes Reinecke <hare@...e.de>,
	Bart Van Assche <bart.vanassche@...disk.com>,
	Sheng Yang <sheng@...ker.org>, linux-scsi@...r.kernel.org,
	target-devel@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: [patch] tcm_loop: use after free on error

We dereference "tl_nexus" to get the error code.

Fixes: 1b418a8fcbc0 ('target: Convert demo-mode only drivers to target_alloc_session')
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>

diff --git a/drivers/target/loopback/tcm_loop.c b/drivers/target/loopback/tcm_loop.c
index 0216c75..e0ffb03 100644
--- a/drivers/target/loopback/tcm_loop.c
+++ b/drivers/target/loopback/tcm_loop.c
@@ -808,6 +808,7 @@ static int tcm_loop_make_nexus(
 {
 	struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba;
 	struct tcm_loop_nexus *tl_nexus;
+	int ret;
 
 	if (tl_tpg->tl_nexus) {
 		pr_debug("tl_tpg->tl_nexus already exists\n");
@@ -824,8 +825,9 @@ static int tcm_loop_make_nexus(
 					TARGET_PROT_DIN_PASS | TARGET_PROT_DOUT_PASS,
 					name, tl_nexus, NULL);
 	if (IS_ERR(tl_nexus->se_sess)) {
+		ret = PTR_ERR(tl_nexus->se_sess);
 		kfree(tl_nexus);
-		return PTR_ERR(tl_nexus->se_sess);
+		return ret;
 	}
 
 	tl_tpg->tl_nexus = tl_nexus;