[PATCH 5.14 411/432] libnvdimm/pmem: Fix crash triggered when I/O in-flight during unbind

Greg Kroah-Hartman
2021-09-16T17:51:58Z

From: sumiyawang <sumiyawang@tencent.com>

commit 32b2397c1e56f33b0b1881def965bb89bd12f448 upstream.

There is a use after free crash when the pmem driver tears down its
mapping while I/O is still inbound.

This is triggered by driver unbind, "ndctl destroy-namespace", while I/O
is in flight.

Fix the sequence of blk_cleanup_queue() vs memunmap().

The crash signature is of the form:

BUG: unable to handle page fault for address: ffffc90080200000
CPU: 36 PID: 9606 Comm: systemd-udevd
Call Trace:
? pmem_do_bvec+0xf9/0x3a0
? xas_alloc+0x55/0xd0
pmem_rw_page+0x4b/0x80
bdev_read_page+0x86/0xb0
do_mpage_readpage+0x5d4/0x7a0
? lru_cache_add+0xe/0x10
mpage_readpages+0xf9/0x1c0
? bd_link_disk_holder+0x1a0/0x1a0
blkdev_readpages+0x1d/0x20
read_pages+0x67/0x1a0

ndctl Call Trace in vmcore:
PID: 23473 TASK: ffff88c4fbbe8000 CPU: 1 COMMAND: "ndctl"
__schedule
schedule
blk_mq_freeze_queue_wait
blk_freeze_queue
blk_cleanup_queue
pmem_release_queue
devm_action_release
release_nodes
devres_release_all
device_release_driver_internal
device_driver_detach
unbind_store

Cc: <stable@vger.kernel.org>
Signed-off-by: sumiyawang <sumiyawang@tencent.com>
Reviewed-by: yongduan <yongduan@tencent.com>
Link: https://lore.kernel.org/r/1629632949-14749-1-git-send-email-sumiyawang@tencent.com
Fixes: 50f44ee7248a ("mm/devm_memremap_pages: fix final page put race")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/nvdimm/pmem.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -450,11 +450,11 @@ static int pmem_attach_disk(struct devic
pmem->pfn_flags |= PFN_MAP;
bb_range = pmem->pgmap.range;
} else {
+ addr = devm_memremap(dev, pmem->phys_addr,
+ pmem->size, ARCH_MEMREMAP_PMEM);
if (devm_add_action_or_reset(dev, pmem_release_queue,
&pmem->pgmap))
return -ENOMEM;
- addr = devm_memremap(dev, pmem->phys_addr,
- pmem->size, ARCH_MEMREMAP_PMEM);
bb_range.start = res->start;
bb_range.end = res->end;
}