[PATCH] afs: Annotate struct afs_addr_list with __counted_by

[PATCH] afs: Annotate struct afs_addr_list with __counted_by

[Kees Cook]

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 afs_addr_list.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: David Howells <dhowells@redhat.com>
Cc: Marc Dionne <marc.dionne@auristor.com>
Cc: linux-afs@lists.infradead.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 fs/afs/internal.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index da73b97e19a9..07433a5349ca 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -87,7 +87,7 @@ struct afs_addr_list {
 	enum dns_lookup_status	status:8;
 	unsigned long		failed;		/* Mask of addrs that failed locally/ICMP */
 	unsigned long		responded;	/* Mask of addrs that responded */
-	struct sockaddr_rxrpc	addrs[];
+	struct sockaddr_rxrpc	addrs[] __counted_by(max_addrs);
 #define AFS_MAX_ADDRESSES ((unsigned int)(sizeof(unsigned long) * 8))
 };
 
-- 
2.34.1

Re: [PATCH] afs: Annotate struct afs_addr_list with __counted_by

[Gustavo A. R. Silva]

On 9/15/23 14:14, 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 afs_addr_list.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: David Howells <dhowells@redhat.com>
> Cc: Marc Dionne <marc.dionne@auristor.com>
> Cc: linux-afs@lists.infradead.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

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

Thanks
-- 
Gustavo

> ---
>   fs/afs/internal.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/afs/internal.h b/fs/afs/internal.h
> index da73b97e19a9..07433a5349ca 100644
> --- a/fs/afs/internal.h
> +++ b/fs/afs/internal.h
> @@ -87,7 +87,7 @@ struct afs_addr_list {
>   	enum dns_lookup_status	status:8;
>   	unsigned long		failed;		/* Mask of addrs that failed locally/ICMP */
>   	unsigned long		responded;	/* Mask of addrs that responded */
> -	struct sockaddr_rxrpc	addrs[];
> +	struct sockaddr_rxrpc	addrs[] __counted_by(max_addrs);
>   #define AFS_MAX_ADDRESSES ((unsigned int)(sizeof(unsigned long) * 8))
>   };
>   

Re: [PATCH] afs: Annotate struct afs_addr_list with __counted_by

[Kees Cook]

On Fri, 15 Sep 2023 13:14:49 -0700, 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 afs_addr_list.
> 
> [...]

Applied to for-next/hardening, thanks!

[1/1] afs: Annotate struct afs_addr_list with __counted_by
      https://git.kernel.org/kees/c/7a709daf5d40

Take care,

-- 
Kees Cook