From: Ming Lei ming.lei@redhat.com

stable inclusion from stable-v6.6.54 commit 6e73b946a379a1dfbb62626af93843bdfb53753d category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAYQRD CVE: CVE-2024-49855

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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[ Upstream commit c9ea57c91f03bcad415e1a20113bdb2077bcf990 ]

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 Reviewed-by: Yu Kuai yukuai3@huawei.com Link: https://lore.kernel.org/r/20240830034145.1827742-1-ming.lei@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: ZhangPeng zhangpeng362@huawei.com Signed-off-by: Zheng Qixing zhengqixing@huawei.com --- 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 8bb5972284b5..74d1f9c26ecc 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); } @@ -461,8 +472,8 @@ 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; }