linux-kernel - [PATCH] sync: Fix memory corruption in sync_timeline

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]

Date:	Tue, 24 Mar 2015 13:55:04 -0700
From:	Alistair Strachan <alistair.strachan@...tec.com>
To:	<linux-kernel@...r.kernel.org>
CC:	Alistair Strachan <alistair.strachan@...tec.com>,
	Maarten Lankhorst <maarten.lankhorst@...onical.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Colin Cross <ccross@...gle.com>
Subject: [PATCH] sync: Fix memory corruption in sync_timeline_signal().

The android_fence_release() function checks for active sync points
by calling list_empty() on the list head embedded on the sync
point. However, it is only valid to use list_empty() on nodes that
have been initialized with INIT_LIST_HEAD() or list_del_init().

Because the list entry has likely been removed from the active list
by sync_timeline_signal(), there is a good chance that this
WARN_ON_ONCE() will be hit due to dangling pointers pointing at
freed memory (even though the sync drivers did nothing wrong)
and memory corruption will ensue as the list entry is removed for
a second time, corrupting the active list.

This problem can be reproduced quite easily with CONFIG_DEBUG_LIST=y
and fences with more than one sync point.

Change-Id: Ie2a6bc1480bbcfdc14f9b385fca5a2b833effc05

Signed-off-by: Alistair Strachan <alistair.strachan@...tec.com>
Cc: Maarten Lankhorst <maarten.lankhorst@...onical.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Colin Cross <ccross@...gle.com>
---
 drivers/staging/android/sync.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/android/sync.c b/drivers/staging/android/sync.c
index 7bdb62b..f83e00c 100644
--- a/drivers/staging/android/sync.c
+++ b/drivers/staging/android/sync.c
@@ -114,7 +114,7 @@ void sync_timeline_signal(struct sync_timeline *obj)
 	list_for_each_entry_safe(pt, next, &obj->active_list_head,
 				 active_list) {
 		if (fence_is_signaled_locked(&pt->base))
-			list_del(&pt->active_list);
+			list_del_init(&pt->active_list);
 	}

 	spin_unlock_irqrestore(&obj->child_list_lock, flags);
-- 
2.1.4

--
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/