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>
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@ -923,16 +923,16 @@ int jbd2_fc_wait_bufs(journal_t *journal, int num_blks)
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for (i = j_fc_off - 1; i >= j_fc_off - num_blks; i--) {
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bh = journal->j_fc_wbuf[i];
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wait_on_buffer(bh);
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put_bh(bh);
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journal->j_fc_wbuf[i] = NULL;
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/*
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* Update j_fc_off so jbd2_fc_release_bufs can release remain
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* buffer head.
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*/
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if (unlikely(!buffer_uptodate(bh))) {
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journal->j_fc_off = i;
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journal->j_fc_off = i + 1;
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return -EIO;
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}
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put_bh(bh);
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journal->j_fc_wbuf[i] = NULL;
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}
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return 0;
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