linux-kernel - [PATCH] Drivers: hv: hv_balloon: keep locks balanced on add

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <1424435367-26384-1-git-send-email-vkuznets@redhat.com>
Date:	Fri, 20 Feb 2015 13:29:27 +0100
From:	Vitaly Kuznetsov <vkuznets@...hat.com>
To:	"K. Y. Srinivasan" <kys@...rosoft.com>,
	devel@...uxdriverproject.org
Cc:	Haiyang Zhang <haiyangz@...rosoft.com>,
	linux-kernel@...r.kernel.org, Dexuan Cui <decui@...rosoft.com>
Subject: [PATCH] Drivers: hv: hv_balloon: keep locks balanced on add_memory() failure

When add_memory() fails the following BUG is observed:
[  743.646107] hv_balloon: hot_add memory failed error is -17
[  743.679973]
[  743.680930] =====================================
[  743.680930] [ BUG: bad unlock balance detected! ]
[  743.680930] 3.19.0-rc5_bug1131426+ #552 Not tainted
[  743.680930] -------------------------------------
[  743.680930] kworker/0:2/255 is trying to release lock (&dm_device.ha_region_mutex) at:
[  743.680930] [<ffffffff81aae5fe>] mutex_unlock+0xe/0x10
[  743.680930] but there are no more locks to release!

This happens as we don't acquire ha_region_mutex and hot_add_req() expects us
to as it does unconditional mutex_unlock(). Acquire the lock on the error path.

Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
This patch is dependent on the previously posted 'Drivers: hv: hv_balloon:
eliminate the trylock path in acquire/release_region_mutex'.
---
 drivers/hv/hv_balloon.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index 1283035..771bf84 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -654,6 +654,7 @@ static void hv_mem_hot_add(unsigned long start, unsigned long size,
 			}
 			has->ha_end_pfn -= HA_CHUNK;
 			has->covered_end_pfn -=  processed_pfn;
+			mutex_lock(&dm_device.ha_region_mutex);
 			break;
 		}
 
-- 
1.9.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/