From e7ec86f54e519e8e86f1cf328db13263f3ef8bd4 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Sat, 18 Apr 2009 17:33:24 +0200 Subject: mac80211: validate TIM IE length (redux) The TIM IE must not be shorter than 4 bytes, so verify that when parsing it and use the proper type. To ease that adjust struct ieee80211_tim_ie to have a virtual bitmap of size at least 1. Also check that the TIM IE is actually present before trying to parse it! Because other people may need the function, make it a static inline in ieee80211.h. (The original "mac80211: validate TIM IE length" was a minimal fix for 2.6.30. This purports to be the full, correct fix. -- JWL) Signed-off-by: Johannes Berg Signed-off-by: John W. Linville --- include/linux/ieee80211.h | 32 +++++++++++++++++++++++++++++++- 1 file changed, 31 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h index 53563d53b5a..c52e7fba4e4 100644 --- a/include/linux/ieee80211.h +++ b/include/linux/ieee80211.h @@ -540,7 +540,7 @@ struct ieee80211_tim_ie { u8 dtim_period; u8 bitmap_ctrl; /* variable size: 1 - 251 bytes */ - u8 virtual_map[0]; + u8 virtual_map[1]; } __attribute__ ((packed)); #define WLAN_SA_QUERY_TR_ID_LEN 16 @@ -1392,4 +1392,34 @@ static inline unsigned long ieee80211_tu_to_usec(unsigned long tu) return 1024 * tu; } +/** + * ieee80211_check_tim - check if AID bit is set in TIM + * @tim: the TIM IE + * @tim_len: length of the TIM IE + * @aid: the AID to look for + */ +static inline bool ieee80211_check_tim(struct ieee80211_tim_ie *tim, + u8 tim_len, u16 aid) +{ + u8 mask; + u8 index, indexn1, indexn2; + + if (unlikely(!tim || tim_len < sizeof(*tim))) + return false; + + aid &= 0x3fff; + index = aid / 8; + mask = 1 << (aid & 7); + + indexn1 = tim->bitmap_ctrl & 0xfe; + indexn2 = tim_len + indexn1 - 4; + + if (index < indexn1 || index > indexn2) + return false; + + index -= indexn1; + + return !!(tim->virtual_map[index] & mask); +} + #endif /* LINUX_IEEE80211_H */ -- cgit v1.2.3-70-g09d2