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_cqm_config.

[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>
---
 net/wireless/core.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/wireless/core.h b/net/wireless/core.h
index 8a807b609ef7..507d184b8b40 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -298,7 +298,7 @@ struct cfg80211_cqm_config {
 	u32 rssi_hyst;
 	s32 last_rssi_event_value;
 	int n_rssi_thresholds;
-	s32 rssi_thresholds[];
+	s32 rssi_thresholds[] __counted_by(n_rssi_thresholds);
 };
 
 void cfg80211_destroy_ifaces(struct cfg80211_registered_device *rdev);
-- 
2.34.1

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_cqm_config.
> 
> [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>

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_cqm_config.
> 
> [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

> ---
>   net/wireless/core.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/wireless/core.h b/net/wireless/core.h
> index 8a807b609ef7..507d184b8b40 100644
> --- a/net/wireless/core.h
> +++ b/net/wireless/core.h
> @@ -298,7 +298,7 @@ struct cfg80211_cqm_config {
>   	u32 rssi_hyst;
>   	s32 last_rssi_event_value;
>   	int n_rssi_thresholds;
> -	s32 rssi_thresholds[];
> +	s32 rssi_thresholds[] __counted_by(n_rssi_thresholds);
>   };
>   
>   void cfg80211_destroy_ifaces(struct cfg80211_registered_device *rdev);