Commit 243d1a5d authored Sep 14, 2022 by Ye Bin Committed by Theodore Ts'o Sep 30, 2022

jbd2: fix potential use-after-free in jbd2_fc_wait_bufs



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>

parent e0d5fc7a

fs/jbd2/journal.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -923,16 +923,16 @@ int jbd2_fc_wait_bufs(journal_t *journal, int num_blks)
		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;