From: Sagi Grimberg <sagi@grimberg.me>
Date: Fri, 2 Aug 2019 20:23:38 -0700
Subject: [PATCH] nvmet-tcp: fix possible NULL deref
References: bsc#1156419,jsc#SLE-8281
Git-commit: b627200762c7e8153fe1620fdd52a68f4ca2f8a5
Patch-mainline: v5.4-rc1

We must only call sgl_free for sgl that we actually
allocated.

Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 drivers/nvme/target/tcp.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
index 69b83fa0c76c..0d63f3da0117 100644
--- a/drivers/nvme/target/tcp.c
+++ b/drivers/nvme/target/tcp.c
@@ -348,7 +348,8 @@ static int nvmet_tcp_map_data(struct nvmet_tcp_cmd *cmd)
 
 	return 0;
 err:
-	sgl_free(cmd->req.sg);
+	if (cmd->req.sg_cnt)
+		sgl_free(cmd->req.sg);
 	return NVME_SC_INTERNAL;
 }
 
@@ -553,7 +554,8 @@ static int nvmet_try_send_data(struct nvmet_tcp_cmd *cmd)
 
 	if (queue->nvme_sq.sqhd_disabled) {
 		kfree(cmd->iov);
-		sgl_free(cmd->req.sg);
+		if (cmd->req.sg_cnt)
+			sgl_free(cmd->req.sg);
 	}
 
 	return 1;
@@ -584,7 +586,8 @@ static int nvmet_try_send_response(struct nvmet_tcp_cmd *cmd,
 		return -EAGAIN;
 
 	kfree(cmd->iov);
-	sgl_free(cmd->req.sg);
+	if (cmd->req.sg_cnt)
+		sgl_free(cmd->req.sg);
 	cmd->queue->snd_cmd = NULL;
 	nvmet_tcp_put_cmd(cmd);
 	return 1;
@@ -1306,7 +1309,8 @@ static void nvmet_tcp_finish_cmd(struct nvmet_tcp_cmd *cmd)
 {
 	nvmet_req_uninit(&cmd->req);
 	nvmet_tcp_unmap_pdu_iovec(cmd);
-	sgl_free(cmd->req.sg);
+	if (cmd->req.sg_cnt)
+		sgl_free(cmd->req.sg);
 }
 
 static void nvmet_tcp_uninit_data_in_cmds(struct nvmet_tcp_queue *queue)
-- 
2.16.4