From e0d5fc7a6d80ac2406c7dfc6bb625201d0250a8a Mon Sep 17 00:00:00 2001
From: Ye Bin <yebin10@huawei.com>
Date: Wed, 14 Sep 2022 18:08:11 +0800
Subject: [PATCH] jbd2: fix potential buffer head reference count leak
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Git-commit: e0d5fc7a6d80ac2406c7dfc6bb625201d0250a8a
Patch-mainline: v6.1-rc1
References: bsc#1207644

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>
Acked-by: Jan Kara <jack@suse.cz>

---
 fs/jbd2/journal.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index f669ae1ff7a2..d00193077bce 100644
--- 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;
-- 
2.35.3