From d11d2ded293976a1a0d9d9471827a44dc9e3c63f Mon Sep 17 00:00:00 2001 From: Ye Bin Date: Wed, 14 Sep 2022 18:08:12 +0800 Subject: [PATCH] jbd2: fix potential use-after-free in jbd2_fc_wait_bufs 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 Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/20220914100812.1414768-3-yebin10@huawei.com Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- fs/jbd2/journal.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index a6efcf5..097ba72 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -924,16 +924,16 @@ 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; -- 2.7.4