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Date:   Tue, 26 Mar 2019 15:29:52 +0900
From:   Greg Kroah-Hartman <>
Cc:     Greg Kroah-Hartman <>,, Jiufei Xue <>,
        Theodore Tso <>,
        Joseph Qi <>,
Subject: [PATCH 4.14 15/41] ext4: fix NULL pointer dereference while journal is aborted

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


From: Jiufei Xue <>

commit fa30dde38aa8628c73a6dded7cb0bba38c27b576 upstream.

We see the following NULL pointer dereference while running xfstests
BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
PGD 8000000c84bad067 P4D 8000000c84bad067 PUD c84e62067 PMD 0
Oops: 0000 [#1] SMP PTI
CPU: 7 PID: 9886 Comm: fsstress Kdump: loaded Not tainted 5.0.0-rc8 #10
RIP: 0010:ext4_do_update_inode+0x4ec/0x760
Call Trace:
? jbd2_journal_get_write_access+0x42/0x50
? __ext4_journal_get_write_access+0x2c/0x70
? ext4_truncate+0x186/0x3f0
? unmap_mapping_pages+0x56/0x100
? generic_permission+0x12b/0x1a0

This is triggered because the NULL pointer handle->h_transaction was
dereferenced in function ext4_update_inode_fsync_trans().
I found that the h_transaction was set to NULL in jbd2__journal_restart
but failed to attached to a new transaction while the journal is aborted.

Fix this by checking the handle before updating the inode.

Fixes: b436b9bef84d ("ext4: Wait for proper transaction commit on fsync")
Signed-off-by: Jiufei Xue <>
Signed-off-by: Theodore Ts'o <>
Reviewed-by: Joseph Qi <>
Signed-off-by: Greg Kroah-Hartman <>

 fs/ext4/ext4_jbd2.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/ext4/ext4_jbd2.h
+++ b/fs/ext4/ext4_jbd2.h
@@ -387,7 +387,7 @@ static inline void ext4_update_inode_fsy
 	struct ext4_inode_info *ei = EXT4_I(inode);
-	if (ext4_handle_valid(handle)) {
+	if (ext4_handle_valid(handle) && !is_handle_aborted(handle)) {
 		ei->i_sync_tid = handle->h_transaction->t_tid;
 		if (datasync)
 			ei->i_datasync_tid = handle->h_transaction->t_tid;

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