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Subject[PATCH] ext4: Fix buffer_head refcnt leak when ext4_iget() fails
Date
ext4_orphan_get() invokes ext4_read_inode_bitmap(), which returns a
reference of the specified buffer_head object to "bitmap_bh" with
increased refcnt.

When ext4_orphan_get() returns, local variable "bitmap_bh" becomes
invalid, so the refcount should be decreased to keep refcount balanced.

The reference counting issue happens in one exception handling path of
ext4_orphan_get(). When ext4_iget() fails, the function forgets to
decrease the refcnt increased by ext4_read_inode_bitmap(), causing a
refcnt leak.

Fix this issue by calling brelse() when ext4_iget() fails.

Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
---
fs/ext4/ialloc.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index f95ee99091e4..2e4729ba17e6 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -1234,6 +1234,7 @@ struct inode *ext4_orphan_get(struct super_block *sb, unsigned long ino)
ext4_set_errno(sb, -err);
ext4_error(sb, "couldn't read orphan inode %lu (err %d)",
ino, err);
+ brelse(bitmap_bh);
return inode;
}

--
2.7.4
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