[PATCH 4.7 36/45] ext4: fix memory leak in ext4_insert_range()

From: Greg Kroah-Hartman
Date: Fri Oct 21 2016 - 05:20:07 EST


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

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

From: Fabian Frederick <fabf@xxxxxxxxx>

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@xxxxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -5734,6 +5734,9 @@ 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,