block: fix use-after-free in block flush handling
A recent commit reused the original request flags for the flush
queue handling. However, for some of the kick flush cases, the
original request was already completed. This caused a use after
free, if blk-mq wasn't used.
Fixes: 84fca1b0c461 ("block: pass failfast and driver-specific flags to flush requests")
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-flush.c b/block/blk-flush.c
index 058abdb..ce41f66 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -169,9 +169,11 @@
struct request_queue *q = rq->q;
struct list_head *pending = &fq->flush_queue[fq->flush_pending_idx];
bool queued = false, kicked;
+ unsigned int cmd_flags;
BUG_ON(rq->flush.seq & seq);
rq->flush.seq |= seq;
+ cmd_flags = rq->cmd_flags;
if (likely(!error))
seq = blk_flush_cur_seq(rq);
@@ -212,7 +214,7 @@
BUG();
}
- kicked = blk_kick_flush(q, fq, rq->cmd_flags);
+ kicked = blk_kick_flush(q, fq, cmd_flags);
return kicked | queued;
}
