On Thu, Aug 17, 2023 at 2:16 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > 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> Reviewed-by: Justin Stitt <justinstitt@xxxxxxxxxx> > --- > 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 >
