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_mbssid_elems. 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 | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h index eb73b5af5d04..5c7d091b3925 100644 --- a/include/net/cfg80211.h +++ b/include/net/cfg80211.h @@ -1187,7 +1187,7 @@ struct cfg80211_mbssid_elems { struct { const u8 *data; size_t len; - } elem[]; + } elem[] __counted_by(cnt); }; /** diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c index 80633e815311..9ba4266368db 100644 --- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -5438,13 +5438,13 @@ nl80211_parse_mbssid_elems(struct wiphy *wiphy, struct nlattr *attrs) elems = kzalloc(struct_size(elems, elem, num_elems), GFP_KERNEL); if (!elems) return ERR_PTR(-ENOMEM); + elems->cnt = num_elems; nla_for_each_nested(nl_elems, attrs, rem_elems) { elems->elem[i].data = nla_data(nl_elems); elems->elem[i].len = nla_len(nl_elems); i++; } - elems->cnt = num_elems; return elems; } -- 2.34.1
