CVE-2026-74336wifi: mac80211: bound S1G TIM PVB walk to the TIM element

Official description

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. Pass the correct element end, (const u8 *)tim + tim_len.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/68cf46755894d495b432e21f9e25637030d8b075
• https://git.kernel.org/stable/c/3abc13ec3ac28c343ad7e7b7496e807b924f0edd
• https://git.kernel.org/stable/c/b224d18b1e5d1cddfc67f63f41d80023b2ec8889