ext4: fix memory leak in ext4_insert_range()

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

Cc: stable@vger.kernel.org
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index d7ccb7f51dfca695040b238a7ceadc256a9d90f4..7f69347bd5a5452e0c0da9f241cd13694a490476 100644 (file)
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -5734,6 +5734,9 @@ int ext4_insert_range(struct inode *inode, loff_t offset, loff_t len)
                        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,