[PATCH] wifi: ath6kl: clamp assoc request/response lengths before subtracting IE offsets

[Doruk Tan Ozturk <doruk@0sec.ai>]

ath6kl_cfg80211_connect_event() subtracts fixed IE offsets from
assoc_req_len (-= 4) and assoc_resp_len (-= 6), both u8, with no lower
bound. The aggregate check recently added to ath6kl_wmi_connect_event_rx()
bounds the declared lengths from above (their sum must fit the received
event), but an assoc request/response shorter than its fixed offset still
underflows here: the u8 wraps to ~250, and cfg80211_connect_result() /
cfg80211_roamed() then treat that wrapped value as the IE length and copy
that many bytes out of the small assoc_info buffer to user space via
nl80211, disclosing adjacent slab memory.

Clamp both lengths to their offsets before subtracting.

Found by 0sec (https://0sec.ai) using automated source analysis; the
missing lower bound is evident from source. Compile-tested.

Fixes: bdcd81707973 ("Add ath6kl cleaned up driver")
Cc: stable@vger.kernel.org
Assisted-by: 0sec:claude-opus-4-8
Signed-off-by: Doruk Tan Ozturk <doruk@0sec.ai>
---
 drivers/net/wireless/ath/ath6kl/cfg80211.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/wireless/ath/ath6kl/cfg80211.c b/drivers/net/wireless/ath/ath6kl/cfg80211.c
index cc0f2c45fc3a..62f663c0daa2 100644
--- a/drivers/net/wireless/ath/ath6kl/cfg80211.c
+++ b/drivers/net/wireless/ath/ath6kl/cfg80211.c
@@ -754,6 +754,11 @@ void ath6kl_cfg80211_connect_event(struct ath6kl_vif *vif, u16 channel,
 	u8 *assoc_resp_ie = assoc_info + beacon_ie_len + assoc_req_len +
 	    assoc_resp_ie_offset;
 
+	if (assoc_req_len < assoc_req_ie_offset)
+		assoc_req_len = assoc_req_ie_offset;
+	if (assoc_resp_len < assoc_resp_ie_offset)
+		assoc_resp_len = assoc_resp_ie_offset;
+
 	assoc_req_len -= assoc_req_ie_offset;
 	assoc_resp_len -= assoc_resp_ie_offset;
 
-- 
2.43.0