From: Jia-Ju Bai <baijiaju1...@gmail.com>

[ Upstream commit 583fee3e12df0e6f1f66f063b989d8e7fed0e65a ]

In ocfs2_write_end_nolock(), there are an if statement on lines 1976,
2047 and 2058, to check whether handle is NULL:

    if (handle)

When handle is NULL, it is used on line 2045:

        ocfs2_update_inode_fsync_trans(handle, inode, 1);
        oi->i_sync_tid = handle->h_transaction->t_tid;

Thus, a possible null-pointer dereference may occur.

To fix this bug, handle is checked before calling
ocfs2_update_inode_fsync_trans().

This bug is found by a static analysis tool STCheck written by us.

Link: http://lkml.kernel.org/r/20190726033705.32307-1-baijiaju1...@gmail.com
Signed-off-by: Jia-Ju Bai <baijiaju1...@gmail.com>
Reviewed-by: Joseph Qi <joseph...@linux.alibaba.com>
Cc: Mark Fasheh <m...@fasheh.com>
Cc: Joel Becker <jl...@evilplan.org>
Cc: Junxiao Bi <junxiao...@oracle.com>
Cc: Changwei Ge <gechang...@live.cn>
Cc: Gang He <g...@suse.com>
Cc: Jun Piao <piao...@huawei.com>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 fs/ocfs2/aops.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index ebeec7530cb60..7de0c9562b707 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -2054,7 +2054,8 @@ int ocfs2_write_end_nolock(struct address_space *mapping,
                inode->i_mtime = inode->i_ctime = current_time(inode);
                di->i_mtime = di->i_ctime = cpu_to_le64(inode->i_mtime.tv_sec);
                di->i_mtime_nsec = di->i_ctime_nsec = 
cpu_to_le32(inode->i_mtime.tv_nsec);
-               ocfs2_update_inode_fsync_trans(handle, inode, 1);
+               if (handle)
+                       ocfs2_update_inode_fsync_trans(handle, inode, 1);
        }
        if (handle)
                ocfs2_journal_dirty(handle, wc->w_di_bh);
-- 
2.20.1

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