On 8/17/23 15:15, Kees Cook 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_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>
Reviewed-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
Thanks
--
Gustavo
---
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;
}
