jbd2: fix potential buffer head reference count leak

As in 'jbd2_fc_wait_bufs' if buffer isn't uptodate, will return -EIO without
update 'journal->j_fc_off'. But 'jbd2_fc_release_bufs' will release buffer head
from ‘j_fc_off - 1’ if 'bh' is NULL will terminal release which will lead to
buffer head buffer head reference count leak.
To solve above issue, update 'journal->j_fc_off' before return -EIO.

Cc: stable@kernel.org
Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220914100812.1414768-2-yebin10@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index f669ae1..d001930 100644 (file)
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -925,8 +925,14 @@ int jbd2_fc_wait_bufs(journal_t *journal, int num_blks)
                wait_on_buffer(bh);
                put_bh(bh);
                journal->j_fc_wbuf[i] = NULL;
-               if (unlikely(!buffer_uptodate(bh)))
+               /*
+                * Update j_fc_off so jbd2_fc_release_bufs can release remain
+                * buffer head.
+                */
+               if (unlikely(!buffer_uptodate(bh))) {
+                       journal->j_fc_off = i;
                        return -EIO;
+               }
        }
 
        return 0;