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[PATCH 3/7] wifi: cfg80211: Annotate struct cfg80211_mbssid_elems with __counted_by

Kees Cook posted 7 patches 2 years, 4 months ago
[PATCH 3/7] wifi: cfg80211: Annotate struct cfg80211_mbssid_elems with __counted_by
Posted by Kees Cook 2 years, 4 months ago 
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@sipsolutions.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 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
Re: [PATCH 3/7] wifi: cfg80211: Annotate struct cfg80211_mbssid_elems with __counted_by
Posted by Jeff Johnson 2 years, 4 months ago 
On 8/17/2023 2:15 PM, 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@sipsolutions.net>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: linux-wireless@vger.kernel.org
> Cc: netdev@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Re: [PATCH 3/7] wifi: cfg80211: Annotate struct cfg80211_mbssid_elems with __counted_by
Posted by Gustavo A. R. Silva 2 years, 4 months ago 

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@sipsolutions.net>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: linux-wireless@vger.kernel.org
> Cc: netdev@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

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;
>   }
>

Patchew 2.1-devel-b67e4c2

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