linux-kernel - Re: [PATCH] seccomp: Fix setting number of loaded filters

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Date:   Wed, 11 Aug 2021 11:46:44 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Wiktor Garbacz <wiktorg@...gle.com>
Cc:     Andy Lutomirski <luto@...capital.net>,
        Will Drewry <wad@...omium.org>, linux-kernel@...r.kernel.org,
        Hsuan-Chi Kuo <hsuanchikuo@...il.com>
Subject: Re: [PATCH] seccomp: Fix setting number of loaded filters

On Tue, Aug 10, 2021 at 02:51:58PM +0200, Wiktor Garbacz wrote:
> The value is only reported through procfs so this
> is purely cosmetic.

Hi,

Thanks for the patch! I thought this had already been fixed, but I see I
dropped the ball. :( Sorry!

I'll get the original fix landed[1], and add you as a reporter.

Out of curiosity, how did you (or Hsuan-Chi Kuo) find this? Broken
behavior, code reading, static analysis?

Thanks!

-Kees

[1] https://lore.kernel.org/lkml/20210304233708.420597-1-hsuanchikuo@gmail.com/

> 
> Signed-off-by: Wiktor Garbacz <wiktorg@...gle.com>
> ---
>  kernel/seccomp.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/seccomp.c b/kernel/seccomp.c
> index 057e17f3215d..6469eca8078c 100644
> --- a/kernel/seccomp.c
> +++ b/kernel/seccomp.c
> @@ -602,7 +602,7 @@ static inline void seccomp_sync_threads(unsigned long flags)
>  		smp_store_release(&thread->seccomp.filter,
>  				  caller->seccomp.filter);
>  		atomic_set(&thread->seccomp.filter_count,
> -			   atomic_read(&thread->seccomp.filter_count));
> +			   atomic_read(&caller->seccomp.filter_count));
>  
>  		/*
>  		 * Don't let an unprivileged task work around
> -- 
> 2.32.0.605.g8dce9f2422-goog
> 

-- 
Kees Cook