linux-kernel - [PATCH 5.0 059/238] vmw_balloon: release lock on error in vmballoon

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Date:   Fri, 22 Mar 2019 12:14:38 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dan Carpenter <dan.carpenter@...cle.com>,
        Nadav Amit <namit@...are.com>
Subject: [PATCH 5.0 059/238] vmw_balloon: release lock on error in vmballoon_reset()

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

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

From: Dan Carpenter <dan.carpenter@...cle.com>

commit d04071a5d6413b65f17f7bd6e2bdb22e22e4ace7 upstream.

We added some locking to this function but forgot to drop the lock on
these two error paths.  This bug would lead to an immediate deadlock.

Fixes: c7b3690fb152 ("vmw_balloon: stats rework")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Cc: stable@...r.kernel.org
Reviewed-by: Nadav Amit <namit@...are.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/misc/vmw_balloon.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/misc/vmw_balloon.c
+++ b/drivers/misc/vmw_balloon.c
@@ -1287,7 +1287,7 @@ static void vmballoon_reset(struct vmbal
 	vmballoon_pop(b);
 
 	if (vmballoon_send_start(b, VMW_BALLOON_CAPABILITIES))
-		return;
+		goto unlock;
 
 	if ((b->capabilities & VMW_BALLOON_BATCHED_CMDS) != 0) {
 		if (vmballoon_init_batching(b)) {
@@ -1298,7 +1298,7 @@ static void vmballoon_reset(struct vmbal
 			 * The guest will retry in one second.
 			 */
 			vmballoon_send_start(b, 0);
-			return;
+			goto unlock;
 		}
 	} else if ((b->capabilities & VMW_BALLOON_BASIC_CMDS) != 0) {
 		vmballoon_deinit_batching(b);
@@ -1314,6 +1314,7 @@ static void vmballoon_reset(struct vmbal
 	if (vmballoon_send_guest_id(b))
 		pr_err("failed to send guest ID to the host\n");
 
+unlock:
 	up_write(&b->conf_sem);
 }