From: Xuanqiang Luo <[email protected]>
mac802154 queues one descriptor per received beacon or MAC command, but
each worker invocation dequeues only one. Since queue_work() coalesces
attempts to queue the same pending work item, a burst can add more
descriptors than scheduled invocations. A later frame may schedule another
invocation, but also adds a descriptor, so it does not necessarily reduce
the backlog. Descriptors can therefore remain queued indefinitely once
reception stops. The RX path, workers, and scan cleanup also access the
descriptor lists without common synchronization.
A queued descriptor carries its receiving interface beyond the RCU
read-side critical section without holding a netdev reference. If the
interface is removed first, the worker can dereference freed memory.
Protect the descriptor lists with a spinlock and keep the workers running
until the queues are empty. Then hold the netdev for the lifetime of each
queued descriptor to prevent it from being freed too early.
This ordering is required. Without the queue-draining fix, a descriptor
stranded by queue_work() coalescing would also strand its netdev reference,
as netdev_put() runs only when the descriptor is released, leaving the
netdev pinned indefinitely.
---
Changes:
v2:
Patch 1 (new):
- Serialize descriptor list access and requeue each worker while another
descriptor remains.
- Detach queued beacons under the same lock before scan cleanup frees
them.
Patch 2:
- Replace the v1 drain_workqueue() approach, which does not cover work
queued after the drain or the DEL_INTERFACE path, with a netdev
reference held by each queued descriptor. (Sashiko.)
v1: https://lore.kernel.org/all/[email protected]/
Xuanqiang Luo (2):
mac802154: serialize and drain queued RX descriptors
mac802154: pin netdevs for queued RX descriptors
include/net/cfg802154.h | 2 ++
net/mac802154/ieee802154_i.h | 2 ++
net/mac802154/main.c | 1 +
net/mac802154/rx.c | 36 ++++++++++++++++++++++++++++++------
net/mac802154/scan.c | 8 +++++++-
5 files changed, 42 insertions(+), 7 deletions(-)
base-commit: dc4b95b8fee95113587e93ca116356032d271371
--
2.43.0
