| Message ID | 20240830034145.1827742-1-ming.lei@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | nbd: fix race between timeout and normal completion | expand |
在 2024/08/30 11:41, Ming Lei 写道: > If request timetout is handled by nbd_requeue_cmd(), normal completion > has to be stopped for avoiding to complete this requeued request, other > use-after-free can be triggered. > > Fix the race by clearing NBD_CMD_INFLIGHT in nbd_requeue_cmd(), meantime > make sure that cmd->lock is grabbed for clearing the flag and the > requeue. > > Cc: Josef Bacik <josef@toxicpanda.com> > Cc: Yu Kuai <yukuai3@huawei.com> > Fixes: 2895f1831e91 ("nbd: don't clear 'NBD_CMD_INFLIGHT' flag if request is not completed") > Signed-off-by: Ming Lei <ming.lei@redhat.com> > --- LGTM Reviewed-by: Yu Kuai <yukuai3@huawei.com> Thanks! > drivers/block/nbd.c | 13 ++++++++++++- > 1 file changed, 12 insertions(+), 1 deletion(-) > > diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c > index 41a90150b501..69b9851b6798 100644 > --- a/drivers/block/nbd.c > +++ b/drivers/block/nbd.c > @@ -181,6 +181,17 @@ static void nbd_requeue_cmd(struct nbd_cmd *cmd) > { > struct request *req = blk_mq_rq_from_pdu(cmd); > > + lockdep_assert_held(&cmd->lock); > + > + /* > + * Clear INFLIGHT flag so that this cmd won't be completed in > + * normal completion path > + * > + * INFLIGHT flag will be set when the cmd is queued to nbd next > + * time. > + */ > + __clear_bit(NBD_CMD_INFLIGHT, &cmd->flags); > + > if (!test_and_set_bit(NBD_CMD_REQUEUED, &cmd->flags)) > blk_mq_requeue_request(req, true); > } > @@ -488,8 +499,8 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req) > nbd_mark_nsock_dead(nbd, nsock, 1); > mutex_unlock(&nsock->tx_lock); > } > - mutex_unlock(&cmd->lock); > nbd_requeue_cmd(cmd); > + mutex_unlock(&cmd->lock); > nbd_config_put(nbd); > return BLK_EH_DONE; > } >
On Fri, 30 Aug 2024 11:41:45 +0800, Ming Lei wrote: > If request timetout is handled by nbd_requeue_cmd(), normal completion > has to be stopped for avoiding to complete this requeued request, other > use-after-free can be triggered. > > Fix the race by clearing NBD_CMD_INFLIGHT in nbd_requeue_cmd(), meantime > make sure that cmd->lock is grabbed for clearing the flag and the > requeue. > > [...] Applied, thanks! [1/1] nbd: fix race between timeout and normal completion commit: c9ea57c91f03bcad415e1a20113bdb2077bcf990 Best regards,
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 41a90150b501..69b9851b6798 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -181,6 +181,17 @@ static void nbd_requeue_cmd(struct nbd_cmd *cmd) { struct request *req = blk_mq_rq_from_pdu(cmd); + lockdep_assert_held(&cmd->lock); + + /* + * Clear INFLIGHT flag so that this cmd won't be completed in + * normal completion path + * + * INFLIGHT flag will be set when the cmd is queued to nbd next + * time. + */ + __clear_bit(NBD_CMD_INFLIGHT, &cmd->flags); + if (!test_and_set_bit(NBD_CMD_REQUEUED, &cmd->flags)) blk_mq_requeue_request(req, true); } @@ -488,8 +499,8 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req) nbd_mark_nsock_dead(nbd, nsock, 1); mutex_unlock(&nsock->tx_lock); } - mutex_unlock(&cmd->lock); nbd_requeue_cmd(cmd); + mutex_unlock(&cmd->lock); nbd_config_put(nbd); return BLK_EH_DONE; }
If request timetout is handled by nbd_requeue_cmd(), normal completion has to be stopped for avoiding to complete this requeued request, other use-after-free can be triggered. Fix the race by clearing NBD_CMD_INFLIGHT in nbd_requeue_cmd(), meantime make sure that cmd->lock is grabbed for clearing the flag and the requeue. Cc: Josef Bacik <josef@toxicpanda.com> Cc: Yu Kuai <yukuai3@huawei.com> Fixes: 2895f1831e91 ("nbd: don't clear 'NBD_CMD_INFLIGHT' flag if request is not completed") Signed-off-by: Ming Lei <ming.lei@redhat.com> --- drivers/block/nbd.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)