[PATCH v3] wifi: mwifiex: validate action frame fixed fields

[Zhao Li <enderaoelyther@gmail.com>]

mwifiex_process_mgmt_packet() accepts an rx_pkt_length as small as a
four-address struct ieee80211_hdr plus the two-byte firmware length prefix.
After stripping the prefix, mwifiex_parse_mgmt_packet() can receive a
buffer equal to sizeof(struct ieee80211_hdr).

For action frames, the parser reads the category byte immediately after
that header and, for a public action frame, reads the following action
code byte without verifying that either field is present. A minimal frame
therefore reads one or two bytes beyond the RX buffer.

Require the category and public action-code fields before reading them.
mwifiex parses the firmware four-address layout before removing addr4,
so add ETH_ALEN to the standard IEEE80211_MIN_ACTION_SIZE() offsets.

Suggested-by: Johannes Berg <johannes@sipsolutions.net>
Fixes: 72e5aa8d2a6d ("mwifiex: support for parsing TDLS discovery frames")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/66f148d83eb9f0970b9abbccc85d1b61244e54ad.camel@sipsolutions.net/
Link: https://lore.kernel.org/all/20260708195911.84365-8-enderaoelyther@gmail.com/
Link: https://lore.kernel.org/all/20260723011013.76968-1-enderaoelyther@gmail.com/
Assisted-by: Codex:gpt-5
Assisted-by: Claude:opus-4.8
Signed-off-by: Zhao Li <enderaoelyther@gmail.com>
---
Changes in v3:
- Drop the redundant parser-local header check; the caller already
  guarantees the complete four-address header after removing the two-byte
  firmware prefix.

Changes in v2:
- Express the action-field sizes with IEEE80211_MIN_ACTION_SIZE(),
  accounting for the firmware four-address layout.
---
 drivers/net/wireless/marvell/mwifiex/util.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/wireless/marvell/mwifiex/util.c b/drivers/net/wireless/marvell/mwifiex/util.c
index 7d3631d21223..e54a86ecaa33 100644
--- a/drivers/net/wireless/marvell/mwifiex/util.c
+++ b/drivers/net/wireless/marvell/mwifiex/util.c
@@ -317,9 +317,15 @@ mwifiex_parse_mgmt_packet(struct mwifiex_private *priv, u8 *payload, u16 len,
 
 	switch (stype) {
 	case IEEE80211_STYPE_ACTION:
+		if (len < IEEE80211_MIN_ACTION_SIZE(category) + ETH_ALEN)
+			return -1;
+
 		category = *(payload + sizeof(struct ieee80211_hdr));
 		switch (category) {
 		case WLAN_CATEGORY_PUBLIC:
+			if (len < IEEE80211_MIN_ACTION_SIZE(action_code) + ETH_ALEN)
+				return -1;
+
 			action_code = *(payload + sizeof(struct ieee80211_hdr)
 					+ 1);
 			if (action_code == WLAN_PUB_ACTION_TDLS_DISCOVER_RES) {
-- 
2.50.1 (Apple Git-155)