nl80211: sanity check the channel switch counter value
The nl80211 channel switch count attribute
(NL80211_ATTR_CH_SWITCH_COUNT) is specified as u32, but the
specification uses u8 for the counter. To make sure strange things
don't happen without informing the user, sanity check the value and
return -EINVAL if it doesn't fit in u8.
Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index cb9f5a4..5839c85 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -5927,6 +5927,7 @@
int err;
bool need_new_beacon = false;
int len, i;
+ u32 cs_count;
if (!rdev->ops->channel_switch ||
!(rdev->wiphy.flags & WIPHY_FLAG_HAS_CHANNEL_SWITCH))
@@ -5963,7 +5964,14 @@
if (need_new_beacon && !info->attrs[NL80211_ATTR_CSA_IES])
return -EINVAL;
- params.count = nla_get_u32(info->attrs[NL80211_ATTR_CH_SWITCH_COUNT]);
+ /* Even though the attribute is u32, the specification says
+ * u8, so let's make sure we don't overflow.
+ */
+ cs_count = nla_get_u32(info->attrs[NL80211_ATTR_CH_SWITCH_COUNT]);
+ if (cs_count > 255)
+ return -EINVAL;
+
+ params.count = cs_count;
if (!need_new_beacon)
goto skip_beacons;