linux-kernel - [PATCH 4.4 18/25] ext4: fix memory leak in ext4_insert

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Message-Id: <20161021091414.162796066@linuxfoundation.org>
Date:   Fri, 21 Oct 2016 11:16:09 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Fabian Frederick <fabf@...net.be>,
        Theodore Tso <tytso@....edu>
Subject: [PATCH 4.4 18/25] ext4: fix memory leak in ext4_insert_range()

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

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

From: Fabian Frederick <fabf@...net.be>

commit edf15aa180d7b98fe16bd3eda42f9dd0e60dee20 upstream.

Running xfstests generic/013 with kmemleak gives the following:

unreferenced object 0xffff8801d3d27de0 (size 96):
  comm "fsstress", pid 4941, jiffies 4294860168 (age 53.485s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 01 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<ffffffff818eaaf3>] kmemleak_alloc+0x23/0x40
    [<ffffffff81179805>] __kmalloc+0xf5/0x1d0
    [<ffffffff8122ef5c>] ext4_find_extent+0x1ec/0x2f0
    [<ffffffff8123530c>] ext4_insert_range+0x34c/0x4a0
    [<ffffffff81235942>] ext4_fallocate+0x4e2/0x8b0
    [<ffffffff81181334>] vfs_fallocate+0x134/0x210
    [<ffffffff8118203f>] SyS_fallocate+0x3f/0x60
    [<ffffffff818efa9b>] entry_SYSCALL_64_fastpath+0x13/0x8f
    [<ffffffffffffffff>] 0xffffffffffffffff

Problem seems mitigated by dropping refs and freeing path
when there's no path[depth].p_ext

Signed-off-by: Fabian Frederick <fabf@...net.be>
Signed-off-by: Theodore Ts'o <tytso@....edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/ext4/extents.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -5738,6 +5738,9 @@ int ext4_insert_range(struct inode *inod
 			up_write(&EXT4_I(inode)->i_data_sem);
 			goto out_stop;
 		}
+	} else {
+		ext4_ext_drop_refs(path);
+		kfree(path);
 	}
 
 	ret = ext4_es_remove_extent(inode, offset_lblk,