From: Keith Yeo keithyjy@gmail.com
commit 6311071a056272e1e761de8d0305e87cc566f734 upstream.
nl80211_parse_mbssid_elems() uses a u8 variable num_elems to count the number of MBSSID elements in the nested netlink attribute attrs, which can lead to an integer overflow if a user of the nl80211 interface specifies 256 or more elements in the corresponding attribute in userspace. The integer overflow can lead to a heap buffer overflow as num_elems determines the size of the trailing array in elems, and this array is thereafter written to for each element in attrs.
Note that this vulnerability only affects devices with the wiphy->mbssid_max_interfaces member set for the wireless physical device struct in the device driver, and can only be triggered by a process with CAP_NET_ADMIN capabilities.
Fix this by checking for a maximum of 255 elements in attrs.
Cc: stable@vger.kernel.org Fixes: dc1e3cb8da8b ("nl80211: MBSSID and EMA support in AP mode") Signed-off-by: Keith Yeo keithyjy@gmail.com Link: https://lore.kernel.org/r/20230731034719.77206-1-keithyjy@gmail.com Signed-off-by: Johannes Berg johannes.berg@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/wireless/nl80211.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -5426,8 +5426,11 @@ nl80211_parse_mbssid_elems(struct wiphy if (!wiphy->mbssid_max_interfaces) return ERR_PTR(-EINVAL);
- nla_for_each_nested(nl_elems, attrs, rem_elems) + nla_for_each_nested(nl_elems, attrs, rem_elems) { + if (num_elems >= 255) + return ERR_PTR(-EINVAL); num_elems++; + }
elems = kzalloc(struct_size(elems, elem, num_elems), GFP_KERNEL); if (!elems)