linux-kernel - [PATCH 5.15 089/530] jbd2: fix potential buffer head reference count leak

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Message-Id: <20221024113049.039697524@linuxfoundation.org>
Date:   Mon, 24 Oct 2022 13:27:13 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, stable@...nel.org,
        Ye Bin <yebin10@...wei.com>, Jan Kara <jack@...e.cz>,
        Theodore Tso <tytso@....edu>
Subject: [PATCH 5.15 089/530] jbd2: fix potential buffer head reference count leak

From: Ye Bin <yebin10@...wei.com>

commit e0d5fc7a6d80ac2406c7dfc6bb625201d0250a8a upstream.

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@...nel.org
Signed-off-by: Ye Bin <yebin10@...wei.com>
Reviewed-by: Jan Kara <jack@...e.cz>
Link: https://lore.kernel.org/r/20220914100812.1414768-2-yebin10@huawei.com
Signed-off-by: Theodore Ts'o <tytso@....edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/jbd2/journal.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -926,8 +926,14 @@ int jbd2_fc_wait_bufs(journal_t *journal
 		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;