linux-kernel - [PATCH] xfs: fix memory leak in xfs_iext_free_last

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Date:   Mon, 20 Nov 2017 17:01:28 +0800
From:   shuwang@...hat.com
To:     darrick.wong@...cle.com, hch@....de
Cc:     linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        bfoster@...hat.com, sandeen@...hat.com, chuhu@...hat.com,
        liwang@...hat.com, yizhan@...hat.com, Shu Wang <shuwang@...hat.com>
Subject: [PATCH] xfs: fix memory leak in xfs_iext_free_last_leaf

From: Shu Wang <shuwang@...hat.com>

found the issue by kmemleak.
unreferenced object 0xffff8800674611c0 (size 16):
    xfs_iext_insert+0x82a/0xa90 [xfs]
    xfs_bmap_add_extent_hole_delay+0x1e5/0x5b0 [xfs]
    xfs_bmapi_reserve_delalloc+0x483/0x530 [xfs]
    xfs_file_iomap_begin+0xac8/0xd40 [xfs]
    iomap_apply+0xb8/0x1b0
    iomap_file_buffered_write+0xac/0xe0
    xfs_file_buffered_aio_write+0x198/0x420 [xfs]
    xfs_file_write_iter+0x23f/0x2a0 [xfs]
    __vfs_write+0x23e/0x340
    vfs_write+0xe9/0x240
    SyS_write+0xa1/0x120
    do_syscall_64+0xda/0x260

Signed-off-by: Shu Wang <shuwang@...hat.com>
---
 fs/xfs/libxfs/xfs_iext_tree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/xfs/libxfs/xfs_iext_tree.c b/fs/xfs/libxfs/xfs_iext_tree.c
index 19e546a41251..89bf16b4d937 100644
--- a/fs/xfs/libxfs/xfs_iext_tree.c
+++ b/fs/xfs/libxfs/xfs_iext_tree.c
@@ -850,9 +850,9 @@ static void
 xfs_iext_free_last_leaf(
 	struct xfs_ifork	*ifp)
 {
-	ifp->if_u1.if_root = NULL;
 	ifp->if_height--;
 	kmem_free(ifp->if_u1.if_root);
+	ifp->if_u1.if_root = NULL;
 }
 
 void
-- 
2.13.5