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jbd2: fix potential use-after-free in jbd2_fc_wait_bufs

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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>
This commit is contained in:
Ye Bin 2022-09-14 18:08:12 +08:00 committed by Theodore Ts'o
parent e0d5fc7a6d
commit 243d1a5d50
1 changed files with 3 additions and 3 deletions
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6
fs/jbd2/journal.c
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@ -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--) { for (i = j_fc_off - 1; i >= j_fc_off - num_blks; i--) {
bh = journal->j_fc_wbuf[i]; bh = journal->j_fc_wbuf[i];
wait_on_buffer(bh); 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 * Update j_fc_off so jbd2_fc_release_bufs can release remain
* buffer head. * buffer head.
*/ */
if (unlikely(!buffer_uptodate(bh))) { if (unlikely(!buffer_uptodate(bh))) {
journal->j_fc_off = i; journal->j_fc_off = i + 1;
return -EIO; return -EIO;
} }
put_bh(bh);
journal->j_fc_wbuf[i] = NULL;
} }
return 0; return 0;