local->assoc_dev is shared between the association path and the association-response worker without common synchronization.
mac802154_perform_association() stores the coordinator pointer and waits for a response. Its timeout and error paths clear the pointer and return to mac802154_associate(), which may then free the coordinator object. Meanwhile, mac802154_rx_mac_cmd_worker() may observe the associating bit and enter mac802154_process_association_resp(), which dereferences assoc_dev. The worker's bit test and the handler's pointer dereference are not atomic with respect to cleanup. Cleanup can clear assoc_dev between them, causing a NULL dereference, or free the coordinator while the response handler still uses the pointer. The response handler only needs the coordinator extended address. Replace assoc_dev with a cached address, removing the pointer lifetime dependency. Protect the cached address and the associating bit with a dedicated spinlock. A READ_ONCE()/WRITE_ONCE() pair would not guarantee an atomic __le64 access on all 32-bit architectures. Reset the completion, publish the cached address, and set the associating bit while holding the lock. Cleanup clears the bit under the same lock. The response handler takes the lock, rechecks the bit, validates the cached address, records the response, and completes the waiter before unlocking. Thus cleanup cannot pass the handler between its state check and completion, and the cached 64-bit value cannot tear. Both users run in process context, so a plain spinlock is sufficient. The lock is not held while waiting for the completion. Suggested-by: Miquel Raynal <[email protected]> Fixes: fefd19807fe9 ("mac802154: Handle associating") Cc: [email protected] Signed-off-by: Kaiwen Shi <[email protected]> --- v2: - cache the coordinator extended address instead of retaining the assoc_dev pointer, as suggested by Miquel; - use a plain spinlock to serialize the cached address and associating bit, including 64-bit address accesses on 32-bit architectures; - reset the completion under the same lock, recheck the associating bit in the response handler, and complete before releasing the lock; - use the response payload in the debug message; - add Cc: [email protected]. Link: https://lore.kernel.org/r/[email protected] net/mac802154/ieee802154_i.h | 3 ++- net/mac802154/main.c | 1 + net/mac802154/scan.c | 21 ++++++++++++++------- 3 files changed, 17 insertions(+), 8 deletions(-) diff --git a/net/mac802154/ieee802154_i.h b/net/mac802154/ieee802154_i.h index 8f2bff268392..8f92ac83f5f9 100644 --- a/net/mac802154/ieee802154_i.h +++ b/net/mac802154/ieee802154_i.h @@ -76,7 +76,8 @@ struct ieee802154_local { struct work_struct rx_mac_cmd_work; /* Association */ - struct ieee802154_pan_device *assoc_dev; + spinlock_t assoc_lock; /* protects association address and active bit */ + __le64 assoc_dev_extended_addr; struct completion assoc_done; __le16 assoc_addr; u8 assoc_status; diff --git a/net/mac802154/main.c b/net/mac802154/main.c index ea1efef3572a..63e89bd586e3 100644 --- a/net/mac802154/main.c +++ b/net/mac802154/main.c @@ -104,6 +104,7 @@ ieee802154_alloc_hw(size_t priv_data_len, const struct ieee802154_ops *ops) INIT_WORK(&local->rx_mac_cmd_work, mac802154_rx_mac_cmd_worker); init_completion(&local->assoc_done); + spin_lock_init(&local->assoc_lock); /* init supported flags with 802.15.4 default ranges */ phy->supported.max_minbe = 8; diff --git a/net/mac802154/scan.c b/net/mac802154/scan.c index 005338f89b75..0ae11e448ccb 100644 --- a/net/mac802154/scan.c +++ b/net/mac802154/scan.c @@ -578,9 +578,11 @@ int mac802154_perform_association(struct ieee802154_sub_if_data *sdata, return ret; } - local->assoc_dev = coord; + spin_lock(&local->assoc_lock); reinit_completion(&local->assoc_done); + local->assoc_dev_extended_addr = coord->extended_addr; set_bit(IEEE802154_IS_ASSOCIATING, &local->ongoing); + spin_unlock(&local->assoc_lock); ret = ieee802154_mlme_tx_one_locked(local, sdata, skb); if (ret) { @@ -616,8 +618,9 @@ int mac802154_perform_association(struct ieee802154_sub_if_data *sdata, *short_addr = local->assoc_addr; clear_assoc: + spin_lock(&local->assoc_lock); clear_bit(IEEE802154_IS_ASSOCIATING, &local->ongoing); - local->assoc_dev = NULL; + spin_unlock(&local->assoc_lock); return ret; } @@ -639,19 +642,23 @@ int mac802154_process_association_resp(struct ieee802154_sub_if_data *sdata, dest->mode != IEEE802154_EXTENDED_ADDRESSING)) return -EINVAL; - if (unlikely(dest->extended_addr != wpan_dev->extended_addr || - src->extended_addr != local->assoc_dev->extended_addr)) + spin_lock(&local->assoc_lock); + if (unlikely(!test_bit(IEEE802154_IS_ASSOCIATING, &local->ongoing) || + dest->extended_addr != wpan_dev->extended_addr || + src->extended_addr != local->assoc_dev_extended_addr)) { + spin_unlock(&local->assoc_lock); return -ENODEV; + } memcpy(&resp_pl, skb->data, sizeof(resp_pl)); local->assoc_addr = resp_pl.short_addr; local->assoc_status = resp_pl.status; + complete(&local->assoc_done); + spin_unlock(&local->assoc_lock); dev_dbg(&skb->dev->dev, "ASSOC RESP 0x%x received from %8phC, getting short address %04x\n", - local->assoc_status, &deaddr, local->assoc_addr); - - complete(&local->assoc_done); + resp_pl.status, &deaddr, resp_pl.short_addr); return 0; } base-commit: 8d3ae59288f1e7d58d76558a6ee96d533bc5019f -- 2.34.1
