7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Daejun Park commit f316aa7f018840523939183425394931b373e4d7 upstream. nvmet_pr_preempt() handles a preempt sent by the reservation holder by changing the reservation type with nvmet_pr_update_reg_attr(), unless the reservation is of an All Registrants type. For the holder that helper does not modify the registrant in place: it puts a copy on the registrant list, points pr->holder to the copy and passes the old registrant to kfree_rcu(). If the reservation type changed, nvmet_pr_preempt() then hands ®->hostid of that old registrant to nvmet_pr_resv_released(). Unless the reservation released notification is masked, that function takes subsys->lock and compares the host id against every controller of the subsystem. The caller only holds pr->pr_sem and is not in an RCU read-side critical section, so nothing keeps the old registrant alive while it is read. The result is a read of 16 freed bytes that decides which controllers get the notification. Found by code inspection. kfree_rcu() defers the free, so it usually happens after the read; when the pending free is forced to run before the read, KASAN reports the host id as freed memory. Pass the host id of the controller that sent the command instead. The registrant was looked up by that host id, and the controller outlives the request. Fixes: 5a47c2080a73 ("nvmet: support reservation feature") Cc: stable@vger.kernel.org Reviewed-by: Christoph Hellwig Signed-off-by: Daejun Park Signed-off-by: Keith Busch Signed-off-by: Greg Kroah-Hartman --- drivers/nvme/target/pr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/nvme/target/pr.c +++ b/drivers/nvme/target/pr.c @@ -593,7 +593,7 @@ static u16 nvmet_pr_preempt(struct nvmet status = nvmet_pr_update_reg_attr(pr, holder, nvmet_pr_update_holder_rtype, &rtype); if (!status && original_rtype != rtype) - nvmet_pr_resv_released(pr, ®->hostid); + nvmet_pr_resv_released(pr, &ctrl->hostid); return status; }