From: Brian Norris briannorris@chromium.org
commit 70e5b8f445fd27fde0c5583460e82539a7242424 upstream.
Before commit 1e58252e334d ("mwifiex: Fix heap overflow in mmwifiex_process_tdls_action_frame()"), mwifiex_process_tdls_action_frame() already had too many magic numbers. But this commit just added a ton more, in the name of checking for buffer overflows. That seems like a really bad idea.
Let's make these magic numbers a little less magic, by (a) factoring out 'pos[1]' as 'ie_len' (b) using 'sizeof' on the appropriate source or destination fields where possible, instead of bare numbers (c) dropping redundant checks, per below.
Regarding redundant checks: the beginning of the loop has this:
if (pos + 2 + pos[1] > end) break;
but then individual 'case's include stuff like this:
if (pos > end - 3) return; if (pos[1] != 1) return;
Note that the second 'return' (validating the length, pos[1]) combined with the above condition (ensuring 'pos + 2 + length' doesn't exceed 'end'), makes the first 'return' (whose 'if' can be reworded as 'pos > end - pos[1] - 2') redundant. Rather than unwind the magic numbers there, just drop those conditions.
Fixes: 1e58252e334d ("mwifiex: Fix heap overflow in mmwifiex_process_tdls_action_frame()") Signed-off-by: Brian Norris briannorris@chromium.org Signed-off-by: Kalle Valo kvalo@codeaurora.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/net/wireless/marvell/mwifiex/tdls.c | 75 ++++++++++------------------ 1 file changed, 28 insertions(+), 47 deletions(-)
--- a/drivers/net/wireless/marvell/mwifiex/tdls.c +++ b/drivers/net/wireless/marvell/mwifiex/tdls.c @@ -894,7 +894,7 @@ void mwifiex_process_tdls_action_frame(s u8 *peer, *pos, *end; u8 i, action, basic; u16 cap = 0; - int ie_len = 0; + int ies_len = 0;
if (len < (sizeof(struct ethhdr) + 3)) return; @@ -916,7 +916,7 @@ void mwifiex_process_tdls_action_frame(s pos = buf + sizeof(struct ethhdr) + 4; /* payload 1+ category 1 + action 1 + dialog 1 */ cap = get_unaligned_le16(pos); - ie_len = len - sizeof(struct ethhdr) - TDLS_REQ_FIX_LEN; + ies_len = len - sizeof(struct ethhdr) - TDLS_REQ_FIX_LEN; pos += 2; break;
@@ -926,7 +926,7 @@ void mwifiex_process_tdls_action_frame(s /* payload 1+ category 1 + action 1 + dialog 1 + status code 2*/ pos = buf + sizeof(struct ethhdr) + 6; cap = get_unaligned_le16(pos); - ie_len = len - sizeof(struct ethhdr) - TDLS_RESP_FIX_LEN; + ies_len = len - sizeof(struct ethhdr) - TDLS_RESP_FIX_LEN; pos += 2; break;
@@ -934,7 +934,7 @@ void mwifiex_process_tdls_action_frame(s if (len < (sizeof(struct ethhdr) + TDLS_CONFIRM_FIX_LEN)) return; pos = buf + sizeof(struct ethhdr) + TDLS_CONFIRM_FIX_LEN; - ie_len = len - sizeof(struct ethhdr) - TDLS_CONFIRM_FIX_LEN; + ies_len = len - sizeof(struct ethhdr) - TDLS_CONFIRM_FIX_LEN; break; default: mwifiex_dbg(priv->adapter, ERROR, "Unknown TDLS frame type.\n"); @@ -947,33 +947,33 @@ void mwifiex_process_tdls_action_frame(s
sta_ptr->tdls_cap.capab = cpu_to_le16(cap);
- for (end = pos + ie_len; pos + 1 < end; pos += 2 + pos[1]) { - if (pos + 2 + pos[1] > end) + for (end = pos + ies_len; pos + 1 < end; pos += 2 + pos[1]) { + u8 ie_len = pos[1]; + + if (pos + 2 + ie_len > end) break;
switch (*pos) { case WLAN_EID_SUPP_RATES: - if (pos[1] > 32) + if (ie_len > sizeof(sta_ptr->tdls_cap.rates)) return; - sta_ptr->tdls_cap.rates_len = pos[1]; - for (i = 0; i < pos[1]; i++) + sta_ptr->tdls_cap.rates_len = ie_len; + for (i = 0; i < ie_len; i++) sta_ptr->tdls_cap.rates[i] = pos[i + 2]; break;
case WLAN_EID_EXT_SUPP_RATES: - if (pos[1] > 32) + if (ie_len > sizeof(sta_ptr->tdls_cap.rates)) return; basic = sta_ptr->tdls_cap.rates_len; - if (pos[1] > 32 - basic) + if (ie_len > sizeof(sta_ptr->tdls_cap.rates) - basic) return; - for (i = 0; i < pos[1]; i++) + for (i = 0; i < ie_len; i++) sta_ptr->tdls_cap.rates[basic + i] = pos[i + 2]; - sta_ptr->tdls_cap.rates_len += pos[1]; + sta_ptr->tdls_cap.rates_len += ie_len; break; case WLAN_EID_HT_CAPABILITY: - if (pos > end - sizeof(struct ieee80211_ht_cap) - 2) - return; - if (pos[1] != sizeof(struct ieee80211_ht_cap)) + if (ie_len != sizeof(struct ieee80211_ht_cap)) return; /* copy the ie's value into ht_capb*/ memcpy((u8 *)&sta_ptr->tdls_cap.ht_capb, pos + 2, @@ -981,59 +981,45 @@ void mwifiex_process_tdls_action_frame(s sta_ptr->is_11n_enabled = 1; break; case WLAN_EID_HT_OPERATION: - if (pos > end - - sizeof(struct ieee80211_ht_operation) - 2) - return; - if (pos[1] != sizeof(struct ieee80211_ht_operation)) + if (ie_len != sizeof(struct ieee80211_ht_operation)) return; /* copy the ie's value into ht_oper*/ memcpy(&sta_ptr->tdls_cap.ht_oper, pos + 2, sizeof(struct ieee80211_ht_operation)); break; case WLAN_EID_BSS_COEX_2040: - if (pos > end - 3) - return; - if (pos[1] != 1) + if (ie_len != sizeof(pos[2])) return; sta_ptr->tdls_cap.coex_2040 = pos[2]; break; case WLAN_EID_EXT_CAPABILITY: - if (pos > end - sizeof(struct ieee_types_header)) - return; - if (pos[1] < sizeof(struct ieee_types_header)) + if (ie_len < sizeof(struct ieee_types_header)) return; - if (pos[1] > 8) + if (ie_len > 8) return; memcpy((u8 *)&sta_ptr->tdls_cap.extcap, pos, sizeof(struct ieee_types_header) + - min_t(u8, pos[1], 8)); + min_t(u8, ie_len, 8)); break; case WLAN_EID_RSN: - if (pos > end - sizeof(struct ieee_types_header)) + if (ie_len < sizeof(struct ieee_types_header)) return; - if (pos[1] < sizeof(struct ieee_types_header)) - return; - if (pos[1] > IEEE_MAX_IE_SIZE - + if (ie_len > IEEE_MAX_IE_SIZE - sizeof(struct ieee_types_header)) return; memcpy((u8 *)&sta_ptr->tdls_cap.rsn_ie, pos, sizeof(struct ieee_types_header) + - min_t(u8, pos[1], IEEE_MAX_IE_SIZE - + min_t(u8, ie_len, IEEE_MAX_IE_SIZE - sizeof(struct ieee_types_header))); break; case WLAN_EID_QOS_CAPA: - if (pos > end - 3) - return; - if (pos[1] != 1) + if (ie_len != sizeof(pos[2])) return; sta_ptr->tdls_cap.qos_info = pos[2]; break; case WLAN_EID_VHT_OPERATION: if (priv->adapter->is_hw_11ac_capable) { - if (pos > end - - sizeof(struct ieee80211_vht_operation) - 2) - return; - if (pos[1] != + if (ie_len != sizeof(struct ieee80211_vht_operation)) return; /* copy the ie's value into vhtoper*/ @@ -1043,10 +1029,7 @@ void mwifiex_process_tdls_action_frame(s break; case WLAN_EID_VHT_CAPABILITY: if (priv->adapter->is_hw_11ac_capable) { - if (pos > end - - sizeof(struct ieee80211_vht_cap) - 2) - return; - if (pos[1] != sizeof(struct ieee80211_vht_cap)) + if (ie_len != sizeof(struct ieee80211_vht_cap)) return; /* copy the ie's value into vhtcap*/ memcpy((u8 *)&sta_ptr->tdls_cap.vhtcap, pos + 2, @@ -1056,9 +1039,7 @@ void mwifiex_process_tdls_action_frame(s break; case WLAN_EID_AID: if (priv->adapter->is_hw_11ac_capable) { - if (pos > end - 4) - return; - if (pos[1] != 2) + if (ie_len != sizeof(u16)) return; sta_ptr->tdls_cap.aid = get_unaligned_le16((pos + 2));