Re: [PATCH 1/1] nl80211: Prevent out-of-bounds read when processing NL80211_ATTR_REG_ALPHA2

From: Jeff Johnson
Date: Fri Apr 01 2022 - 14:35:47 EST

On 4/1/2022 3:50 AM, Lee Jones wrote:
Checks are presently in place in validate_nla() to ensure strings
greater than 2 are not passed in by the user which could potentially
cause issues.

However, there is nothing to prevent userspace from only providing a
single (1) Byte as the data length parameter via nla_put(). If this
were to happen, it would cause an OOB read in regulatory_hint_user(),
since it makes assumptions that alpha2[0] and alpha2[1] will always be

Add an additional check, to ensure enough data has been allocated to
hold both Bytes.

Cc: <stable@xxxxxxxxxxxxxxx>
Cc: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
Cc: linux-wireless@xxxxxxxxxxxxxxx
Cc: netdev@xxxxxxxxxxxxxxx
Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
net/wireless/nl80211.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index ee1c2b6b69711..80a516033db36 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -7536,6 +7536,10 @@ static int nl80211_req_set_reg(struct sk_buff *skb, struct genl_info *info)
if (!info->attrs[NL80211_ATTR_REG_ALPHA2])
return -EINVAL;
+ if (nla_len(info->attrs[NL80211_ATTR_REG_ALPHA2]) !=
+ nl80211_policy[NL80211_ATTR_REG_ALPHA2].len)
+ return -EINVAL;
data = nla_data(info->attrs[NL80211_ATTR_REG_ALPHA2]);
return regulatory_hint_user(data, user_reg_hint_type);


doesn't nl80211_set_reg() also have this issue?
alpha2 = nla_data(info->attrs[NL80211_ATTR_REG_ALPHA2]);
rd->alpha2[0] = alpha2[0];
rd->alpha2[1] = alpha2[1];