Medium [CVE-2026-74336] bound S1G TIM PVB walk to the TIM element

In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: bound S1G TIM PVB walk to the TIM element ieee80211_s1g_check_tim() parses the S1G Partial Virtual Bitmap (PVB) of a received TIM element.

The TIM is handed in as the element payload: ieee802_11_parse_elems_full() stores elems->tim = elem->data and elems->tim_len = elem->datalen (net/mac80211/parse.c), so the valid bytes are [tim, tim + tim_len).

When walking the encoded blocks the function passes the walker an end sentinel of (const u8 *)tim + tim_len + 2, i.e. two bytes past the end of the element. ieee80211_s1g_find_target_block() loops while (ptr + 1 <= end) and dereferences ptr (and the per-mode ieee80211_s1g_len_*() helpers read *ptr), so it can read up to two bytes beyond the TIM element -- an out-of-bounds read of adjacent skb/heap data when the TIM is the last element in the frame.

The +2 appears to account for the element id/len header, but tim already points past that header at the element payload, so the addend is wrong. An out-of-bounds read vulnerability exists when parsing the S1G (Sub-1 GHz) TIM (Traffic Indication Map) Partial Virtual Bitmap (PVB) element.

Due to an incorrect boundary check, the system can read two bytes beyond the allocated memory for the TIM element. This could lead to the disclosure of sensitive adjacent kernel memory data.