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Date: Wed, 14 Sep 2022 18:08:12 +0800 From: Ye Bin <yebin10@...wei.com> To: <tytso@....edu>, <adilger.kernel@...ger.ca>, <linux-ext4@...r.kernel.org> CC: <linux-kernel@...r.kernel.org>, <jack@...e.cz>, Ye Bin <yebin10@...wei.com> Subject: [PATCH -next 2/2] 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. Signed-off-by: Ye Bin <yebin10@...wei.com> --- 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 1c833d8cb0fe..4d49f629d06b 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -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; -- 2.31.1
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