[Ocfs2-devel] [PATCH] ocfs2: fix possible double free in ocfs2_write_begin_nolock

[Xue jiufei]

When ocfs2_write_cluster_by_desc() failed in ocfs2_write_begin_nolock()
because of ENOSPC, it goes to out_quota, freeing data_ac(meta_ac). Then
it calls ocfs2_try_to_free_truncate_log() to free space. If enough
space freed, it will try to write again. Unfortunately, some error
happenes before ocfs2_lock_allocators(), it goes to out and free 
data_ac(meta_ac) again.

Signed-off-by: joyce <xuejiufei at huawei.com>
---
 fs/ocfs2/aops.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index f37d3c0..8ad0a41 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -1897,10 +1897,14 @@ out_commit:
 out:
 	ocfs2_free_write_ctxt(wc);
 
-	if (data_ac)
+	if (data_ac) {
 		ocfs2_free_alloc_context(data_ac);
-	if (meta_ac)
+		data_ac = NULL;
+	}
+	if (meta_ac) {
 		ocfs2_free_alloc_context(meta_ac);
+		meta_ac = NULL;
+	}
 
 	if (ret == -ENOSPC && try_free) {
 		/*
-- 
1.7.9.7