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author | Ming Lei <ming.lei@redhat.com> | 2021-05-11 18:22:34 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-07-14 17:55:58 +0300 |
commit | a3362ff0433b9cbd545c35baae59c5788b766e53 (patch) | |
tree | 90eedce510e877672596c1eca87165c766ae45be /block/blk-mq.c | |
parent | f58625bf2ca9d8ecdd02c8021d754a7d437c207f (diff) | |
download | linux-a3362ff0433b9cbd545c35baae59c5788b766e53.tar.xz |
blk-mq: grab rq->refcount before calling ->fn in blk_mq_tagset_busy_iter
[ Upstream commit 2e315dc07df009c3e29d6926871f62a30cfae394 ]
Grab rq->refcount before calling ->fn in blk_mq_tagset_busy_iter(), and
this way will prevent the request from being re-used when ->fn is
running. The approach is same as what we do during handling timeout.
Fix request use-after-free(UAF) related with completion race or queue
releasing:
- If one rq is referred before rq->q is frozen, then queue won't be
frozen before the request is released during iteration.
- If one rq is referred after rq->q is frozen, refcount_inc_not_zero()
will return false, and we won't iterate over this request.
However, still one request UAF not covered: refcount_inc_not_zero() may
read one freed request, and it will be handled in next patch.
Tested-by: John Garry <john.garry@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20210511152236.763464-3-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'block/blk-mq.c')
-rw-r--r-- | block/blk-mq.c | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c index 4bf9449b4586..50d3527a5d97 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -927,6 +927,14 @@ static bool blk_mq_req_expired(struct request *rq, unsigned long *next) return false; } +void blk_mq_put_rq_ref(struct request *rq) +{ + if (is_flush_rq(rq, rq->mq_hctx)) + rq->end_io(rq, 0); + else if (refcount_dec_and_test(&rq->ref)) + __blk_mq_free_request(rq); +} + static bool blk_mq_check_expired(struct blk_mq_hw_ctx *hctx, struct request *rq, void *priv, bool reserved) { @@ -960,11 +968,7 @@ static bool blk_mq_check_expired(struct blk_mq_hw_ctx *hctx, if (blk_mq_req_expired(rq, next)) blk_mq_rq_timed_out(rq, reserved); - if (is_flush_rq(rq, hctx)) - rq->end_io(rq, 0); - else if (refcount_dec_and_test(&rq->ref)) - __blk_mq_free_request(rq); - + blk_mq_put_rq_ref(rq); return true; } |