wifi: mac80211_hwsim: reject undersized HWSIM_ATTR_TX_INFO

hwsim_tx_info_frame_received_nl() casts the HWSIM_ATTR_TX_INFO payload
to a struct hwsim_tx_rate * and unconditionally reads
IEEE80211_TX_MAX_RATES entries (8 bytes) from it. The policy only bounds
the attribute from above (NLA_BINARY .len is a maximum) and the op sets
GENL_DONT_VALIDATE_STRICT, so a short or zero-length attribute is
accepted and the loop reads past the payload.

Require the exact length in the policy, so a malformed attribute is
rejected before the handler runs.

Signed-off-by: Ibrahim Hashimov <security@auditcode.ai>
Assisted-by: AuditCode-AI:2026.07
Link: https://patch.msgid.link/20260721115346.17236-1-security@auditcode.ai
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/drivers/net/wireless/virtual/mac80211_hwsim_main.c b/drivers/net/wireless/virtual/mac80211_hwsim_main.c
index 956ff9b94526daa04bcb93997f47e07aa517630f..75caa97becc8dd04bd9aebae3840cda5f6481d5e 100644 (file)
--- a/drivers/net/wireless/virtual/mac80211_hwsim_main.c
+++ b/drivers/net/wireless/virtual/mac80211_hwsim_main.c
@@ -870,9 +870,9 @@ static const struct nla_policy hwsim_genl_policy[HWSIM_ATTR_MAX + 1] = {
        [HWSIM_ATTR_FLAGS] = { .type = NLA_U32 },
        [HWSIM_ATTR_RX_RATE] = { .type = NLA_U32 },
        [HWSIM_ATTR_SIGNAL] = { .type = NLA_U32 },
-       [HWSIM_ATTR_TX_INFO] = { .type = NLA_BINARY,
-                                .len = IEEE80211_TX_MAX_RATES *
-                                       sizeof(struct hwsim_tx_rate)},
+       [HWSIM_ATTR_TX_INFO] =
+               NLA_POLICY_EXACT_LEN(IEEE80211_TX_MAX_RATES *
+                                    sizeof(struct hwsim_tx_rate)),
        [HWSIM_ATTR_COOKIE] = { .type = NLA_U64 },
        [HWSIM_ATTR_CHANNELS] = { .type = NLA_U32 },
        [HWSIM_ATTR_RADIO_ID] = { .type = NLA_U32 },