ecryptfs: Annotate struct ecryptfs_message with __counted_by

[PATCH] ecryptfs: Annotate struct ecryptfs_message with __counted_by

Posted by Thorsten Blum 3 weeks, 5 days ago

Add the __counted_by() compiler attribute to the flexible array member
'data' to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and
CONFIG_FORTIFY_SOURCE.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
 fs/ecryptfs/ecryptfs_kernel.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index 62a2ea7f59ed..f58b12be8267 100644
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -359,7 +359,7 @@ struct ecryptfs_message {
 	/* Inherits from msg_ctx->index */
 	u32 index;
 	u32 data_len;
-	u8 data[];
+	u8 data[] __counted_by(data_len);
 };
 
 struct ecryptfs_msg_ctx {
-- 
Thorsten Blum <thorsten.blum@linux.dev>
GPG: 1D60 735E 8AEF 3BE4 73B6  9D84 7336 78FD 8DFE EAD4

Re: [PATCH] ecryptfs: Annotate struct ecryptfs_message with __counted_by

Posted by Kees Cook 3 weeks, 4 days ago

On Mon, 12 Jan 2026 12:53:11 +0100, Thorsten Blum wrote:
> Add the __counted_by() compiler attribute to the flexible array member
> 'data' to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and
> CONFIG_FORTIFY_SOURCE.
> 
> 

Applied to for-next/hardening, thanks!

[1/1] ecryptfs: Annotate struct ecryptfs_message with __counted_by
      https://git.kernel.org/kees/c/574d944d2ff3

Take care,

-- 
Kees Cook

Re: [PATCH] ecryptfs: Annotate struct ecryptfs_message with __counted_by

Posted by Tyler Hicks 3 weeks, 4 days ago

On 2026-01-12 12:53:11, Thorsten Blum wrote:
> Add the __counted_by() compiler attribute to the flexible array member
> 'data' to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and
> CONFIG_FORTIFY_SOURCE.
> 
> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>

Nice! I wasn't aware of this attribute. I'm surprised it isn't
documented under Documentation/.

Acked-by: Tyler Hicks <code@tyhicks.com>

Thank you!

Tyler

> ---
>  fs/ecryptfs/ecryptfs_kernel.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
> index 62a2ea7f59ed..f58b12be8267 100644
> --- a/fs/ecryptfs/ecryptfs_kernel.h
> +++ b/fs/ecryptfs/ecryptfs_kernel.h
> @@ -359,7 +359,7 @@ struct ecryptfs_message {
>  	/* Inherits from msg_ctx->index */
>  	u32 index;
>  	u32 data_len;
> -	u8 data[];
> +	u8 data[] __counted_by(data_len);
>  };
>  
>  struct ecryptfs_msg_ctx {
> -- 
> Thorsten Blum <thorsten.blum@linux.dev>
> GPG: 1D60 735E 8AEF 3BE4 73B6  9D84 7336 78FD 8DFE EAD4
>