[PATCH 5.19 120/717] jbd2: fix potential use-after-free in jbd2_fc_wait_bufs

Greg Kroah-Hartman
2022-10-22T07:48:51Z

From: Ye Bin <yebin10@huawei.com>

commit 243d1a5d505d0b0460c9af0ad56ed4a56ef0bebd upstream.

In 'jbd2_fc_wait_bufs' use 'bh' after put buffer head reference count
which may lead to use-after-free.
So judge buffer if uptodate before put buffer head reference count.

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/20220914100812.1414768-3-yebin10@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/jbd2/journal.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -926,16 +926,16 @@ int jbd2_fc_wait_bufs(journal_t *journal
for (i = j_fc_off - 1; i >= j_fc_off - num_blks; i--) {
bh = journal->j_fc_wbuf[i];
wait_on_buffer(bh);
- put_bh(bh);
- journal->j_fc_wbuf[i] = NULL;
/*
* Update j_fc_off so jbd2_fc_release_bufs can release remain
* buffer head.
*/
if (unlikely(!buffer_uptodate(bh))) {
- journal->j_fc_off = i;
+ journal->j_fc_off = i + 1;
return -EIO;
}
+ put_bh(bh);
+ journal->j_fc_wbuf[i] = NULL;
}

return 0;