From: Johannes Berg Date: Sat, 18 Apr 2009 15:33:24 +0000 (+0200) Subject: mac80211: validate TIM IE length (redux) X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=e7ec86f54e519e8e86f1cf328db13263f3ef8bd4;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git 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 --- diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h index 53563d53b5ad..c52e7fba4e40 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 */ diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h index dba78d89a10c..1579bc92c88d 100644 --- a/net/mac80211/ieee80211_i.h +++ b/net/mac80211/ieee80211_i.h @@ -832,7 +832,7 @@ struct ieee802_11_elems { u8 *fh_params; u8 *ds_params; u8 *cf_params; - u8 *tim; + struct ieee80211_tim_ie *tim; u8 *ibss_params; u8 *challenge; u8 *wpa; diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c index 428742d7f440..1b0b7aa387ee 100644 --- a/net/mac80211/mlme.c +++ b/net/mac80211/mlme.c @@ -675,30 +675,6 @@ static void ieee80211_sta_wmm_params(struct ieee80211_local *local, } } -static bool ieee80211_check_tim(struct ieee802_11_elems *elems, u16 aid) -{ - u8 mask; - u8 index, indexn1, indexn2; - struct ieee80211_tim_ie *tim = (struct ieee80211_tim_ie *) elems->tim; - - if (unlikely(!tim || elems->tim_len < 4)) - return false; - - aid &= 0x3fff; - index = aid / 8; - mask = 1 << (aid & 7); - - indexn1 = tim->bitmap_ctrl & 0xfe; - indexn2 = elems->tim_len + indexn1 - 4; - - if (index < indexn1 || index > indexn2) - return false; - - index -= indexn1; - - return !!(tim->virtual_map[index] & mask); -} - static u32 ieee80211_handle_bss_capability(struct ieee80211_sub_if_data *sdata, u16 capab, bool erp_valid, u8 erp) { @@ -1806,7 +1782,8 @@ static void ieee80211_rx_mgmt_beacon(struct ieee80211_sub_if_data *sdata, care_about_ies, ncrc); if (local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK) - directed_tim = ieee80211_check_tim(&elems, ifmgd->aid); + directed_tim = ieee80211_check_tim(elems.tim, elems.tim_len, + ifmgd->aid); ncrc = crc32_be(ncrc, (void *)&directed_tim, sizeof(directed_tim)); diff --git a/net/mac80211/util.c b/net/mac80211/util.c index 11244212f41d..61876eb50b49 100644 --- a/net/mac80211/util.c +++ b/net/mac80211/util.c @@ -588,8 +588,10 @@ u32 ieee802_11_parse_elems_crc(u8 *start, size_t len, elems->cf_params_len = elen; break; case WLAN_EID_TIM: - elems->tim = pos; - elems->tim_len = elen; + if (elen >= sizeof(struct ieee80211_tim_ie)) { + elems->tim = (void *)pos; + elems->tim_len = elen; + } break; case WLAN_EID_IBSS_PARAMS: elems->ibss_params = pos;