[PATCH 5.4 48/56] libnvdimm/pmem: Fix crash triggered when I/O in-flight during unbind

Greg Kroah-Hartman
2021-10-04T13:18:38Z

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>
[tyhicks: Minor contextual change in pmem_attach_disk() due to the
transition to 'struct range' not yet taking place. Preserve the
memcpy() call rather than initializing the range struct. That change
was introduced in v5.10 with commit a4574f63edc6 ("mm/memremap_pages:
convert to 'struct range'")]
Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.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
@@ -423,11 +423,11 @@ static int pmem_attach_disk(struct devic
pmem->pfn_flags |= PFN_MAP;
memcpy(&bb_res, &pmem->pgmap.res, sizeof(bb_res));
} 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);
memcpy(&bb_res, &nsio->res, sizeof(bb_res));
}