Prepare for the coming implementation by GCC and Clang of the __counted_by attribute. Flexible array members annotated with __counted_by can have their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family functions). As found with Coccinelle[1], add __counted_by for struct cfg80211_acl_data. Additionally, since the element count member must be set before accessing the annotated flexible array member, move its initialization earlier. [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci Cc: Johannes Berg <johannes@xxxxxxxxxxxxxxxx> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx> Cc: Eric Dumazet <edumazet@xxxxxxxxxx> Cc: Jakub Kicinski <kuba@xxxxxxxxxx> Cc: Paolo Abeni <pabeni@xxxxxxxxxx> Cc: linux-wireless@xxxxxxxxxxxxxxx Cc: netdev@xxxxxxxxxxxxxxx Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> --- include/net/cfg80211.h | 2 +- net/wireless/nl80211.c | 3 +-- 2 files changed, 2 insertions(+), 3 deletions(-) diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h index d6fa7c8767ad..eb73b5af5d04 100644 --- a/include/net/cfg80211.h +++ b/include/net/cfg80211.h @@ -1282,7 +1282,7 @@ struct cfg80211_acl_data { int n_acl_entries; /* Keep it last */ - struct mac_address mac_addrs[]; + struct mac_address mac_addrs[] __counted_by(n_acl_entries); }; /** diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c index 8bcf8e293308..80633e815311 100644 --- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -4889,13 +4889,12 @@ static struct cfg80211_acl_data *parse_acl_data(struct wiphy *wiphy, acl = kzalloc(struct_size(acl, mac_addrs, n_entries), GFP_KERNEL); if (!acl) return ERR_PTR(-ENOMEM); + acl->n_acl_entries = n_entries; nla_for_each_nested(attr, info->attrs[NL80211_ATTR_MAC_ADDRS], tmp) { memcpy(acl->mac_addrs[i].addr, nla_data(attr), ETH_ALEN); i++; } - - acl->n_acl_entries = n_entries; acl->acl_policy = acl_policy; return acl; -- 2.34.1
