In the `mac802154_scan_worker` function, the `scan_req->type` field was accessed after the RCU read-side critical section was unlocked. According to RCU usage rules, this is illegal and can lead to unpredictable behavior, such as accessing memory that has been updated or causing use-after-free issues.

This possible bug was identified using a static analysis tool developed by myself, specifically designed to detect RCU-related issues.

To address this, the `scan_req->type` value is now stored in a local variable `scan_req_type` while still within the RCU read-side critical section. The `scan_req_type` is then used after the RCU lock is released, ensuring that the type value is safely accessed without violating RCU rules.

Fixes: e2c3e6f53a7a ("mac802154: Handle active scanning") Signed-off-by: Jiawei Ye jiawei.ye@foxmail.com Cc: stable@vger.kernel.org Acked-by: Miquel Raynal miquel.raynal@bootlin.com --- Changelog:

v1->v2: -Repositioned the enum nl802154_scan_types scan_req_type declaration between struct cfg802154_scan_request *scan_req and struct ieee802154_sub_if_data *sdata to comply with the reverse Christmas tree rule. --- net/mac802154/scan.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/mac802154/scan.c b/net/mac802154/scan.c index 1c0eeaa76560..a6dab3cc3ad8 100644 --- a/net/mac802154/scan.c +++ b/net/mac802154/scan.c @@ -176,6 +176,7 @@ void mac802154_scan_worker(struct work_struct *work) struct ieee802154_local *local = container_of(work, struct ieee802154_local, scan_work.work); struct cfg802154_scan_request *scan_req; + enum nl802154_scan_types scan_req_type; struct ieee802154_sub_if_data *sdata; unsigned int scan_duration = 0; struct wpan_phy *wpan_phy; @@ -209,6 +210,7 @@ void mac802154_scan_worker(struct work_struct *work) }

wpan_phy = scan_req->wpan_phy; + scan_req_type = scan_req->type; scan_req_duration = scan_req->duration;

/* Look for the next valid chan */ @@ -246,7 +248,7 @@ void mac802154_scan_worker(struct work_struct *work) goto end_scan; }

- if (scan_req->type == NL802154_SCAN_ACTIVE) { + if (scan_req_type == NL802154_SCAN_ACTIVE) { ret = mac802154_transmit_beacon_req(local, sdata); if (ret) dev_err(&sdata->dev->dev,