FAILED: patch "[PATCH] libnvdimm/pmem: Fix crash triggered when I/O in-flight during" failed to apply to 5.4-stable tree

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 32b2397c1e56f33b0b1881def965bb89bd12f448 Mon Sep 17 00:00:00 2001
From: sumiyawang <[email protected]>
Date: Sun, 22 Aug 2021 19:49:09 +0800
Subject: [PATCH] libnvdimm/pmem: Fix crash triggered when I/O in-flight during
unbind

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

index 1e0615b8565e..72de88ff0d30 100644
@@ -450,11 +450,11 @@ static int pmem_attach_disk(struct device *dev,
 		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;
 	}

From: sumiyawang <[email protected]>

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

[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'")]

---

We're seeing memory corruption issues in production and, AFAICT, we exercise this bit of code around the time that the corruption takes place. Therefore, I'm submitting this manually tested backport for inclusion in linux-5.4.y since it wasn't automatically applied due to the need for a manual backport.

 drivers/nvdimm/pmem.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

index f9f76f6ba07b..7e65306b2bf2 100644
@@ -423,11 +423,11 @@ static int pmem_attach_disk(struct device *dev,
 		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));
 	}
 

2.25.1

Now queued up, thanks.

greg k-h