wifi: cfg80211: reject duplicate wiphy cipher suite entries

Duplicate entries in wiphy->cipher_suites do not describe any
additional capability, but cfg80211 currently accepts them and leaves
individual consumers to deal with them.

One such consumer is the WEXT compatibility code, which appends a WEP
key length for each WEP cipher entry it sees. Repeated WEP entries can
therefore overflow the fixed iw_range::encoding_size array returned by
SIOCGIWRANGE.

Reject duplicate cipher suite entries in wiphy_register() instead.
This keeps the cipher suite invariant in one place and makes malformed
wiphy descriptions fail early with -EINVAL, rather than relying on a
single cfg80211 user to handle duplicates correctly.

Reported-by: Yifan Wu <yifanwucs@gmail.com>
Reported-by: Juefei Pu <tomapufckgml@gmail.com>
Co-developed-by: Yuan Tan <yuantan098@gmail.com>
Signed-off-by: Yuan Tan <yuantan098@gmail.com>
Suggested-by: Xin Liu <bird@lzu.edu.cn>
Signed-off-by: Yuqi Xu <xuyuqiabc@gmail.com>
Signed-off-by: Ren Wei <n05ec@lzu.edu.cn>
Link: https://patch.msgid.link/20260413123000.1480661-1-n05ec@lzu.edu.cn
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/net/wireless/core.c b/net/wireless/core.c
index 6783e0672dcb..345a83fe428f 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -804,6 +804,24 @@ static int wiphy_verify_combinations(struct wiphy *wiphy)
 	return ret;
 }
 
+static bool wiphy_cipher_suites_valid(const struct wiphy *wiphy)
+{
+	int i, j;
+
+	if (wiphy->n_cipher_suites && !wiphy->cipher_suites)
+		return false;
+
+	for (i = 0; i < wiphy->n_cipher_suites; i++) {
+		for (j = 0; j < i; j++) {
+			if (wiphy->cipher_suites[i] ==
+			    wiphy->cipher_suites[j])
+				return false;
+		}
+	}
+
+	return true;
+}
+
 int wiphy_register(struct wiphy *wiphy)
 {
 	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
@@ -940,6 +958,9 @@ int wiphy_register(struct wiphy *wiphy)
 	if (res)
 		return res;
 
+	if (!wiphy_cipher_suites_valid(wiphy))
+		return -EINVAL;
+
 	/* sanity check supported bands/channels */
 	for (band = 0; band < NUM_NL80211_BANDS; band++) {
 		const struct ieee80211_sband_iftype_data *iftd;