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From: Baoquan He <bhe@redhat.com>
To: Kees Cook <keescook@chromium.org>
Cc: Eric Biederman <ebiederm@xmission.com>,
	kexec@lists.infradead.org, Vivek Goyal <vgoyal@redhat.com>,
	Dave Young <dyoung@redhat.com>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Tom Rix <trix@redhat.com>,
	linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
	linux-hardening@vger.kernel.org
Subject: Re: [PATCH] kexec: Annotate struct crash_mem with __counted_by
Date: Sat, 23 Sep 2023 08:46:47 +0800	[thread overview]
Message-ID: <ZQ41d5majBepW48Z@MiWiFi-R3L-srv> (raw)
In-Reply-To: <20230922175224.work.712-kees@kernel.org>

On 09/22/23 at 10:52am, 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 crash_mem.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Eric Biederman <ebiederm@xmission.com>
> Cc: kexec@lists.infradead.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  include/linux/crash_core.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> index 3426f6eef60b..5126a4fecb44 100644
> --- a/include/linux/crash_core.h
> +++ b/include/linux/crash_core.h
> @@ -131,7 +131,7 @@ static inline void __init reserve_crashkernel_generic(char *cmdline,
>  struct crash_mem {
>  	unsigned int max_nr_ranges;
>  	unsigned int nr_ranges;
> -	struct range ranges[];
> +	struct range ranges[] __counted_by(max_nr_ranges);

This __counted_by() only makes sense when there's a obvious upper
boundary, max_nr_ranges in this case. This heavily depends and isn't
much in kernel? E.g struct swap_info_struct->avail_lists[]. Just
curious, not related to this patch though.

>  };
>  
>  extern int crash_exclude_mem_range(struct crash_mem *mem,
> -- 
> 2.34.1
> 


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WARNING: multiple messages have this Message-ID (diff)
From: Baoquan He <bhe@redhat.com>
To: Kees Cook <keescook@chromium.org>
Cc: Eric Biederman <ebiederm@xmission.com>,
	kexec@lists.infradead.org, Vivek Goyal <vgoyal@redhat.com>,
	Dave Young <dyoung@redhat.com>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Tom Rix <trix@redhat.com>,
	linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
	linux-hardening@vger.kernel.org
Subject: Re: [PATCH] kexec: Annotate struct crash_mem with __counted_by
Date: Sat, 23 Sep 2023 08:46:47 +0800	[thread overview]
Message-ID: <ZQ41d5majBepW48Z@MiWiFi-R3L-srv> (raw)
In-Reply-To: <20230922175224.work.712-kees@kernel.org>

On 09/22/23 at 10:52am, 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 crash_mem.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Eric Biederman <ebiederm@xmission.com>
> Cc: kexec@lists.infradead.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  include/linux/crash_core.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> index 3426f6eef60b..5126a4fecb44 100644
> --- a/include/linux/crash_core.h
> +++ b/include/linux/crash_core.h
> @@ -131,7 +131,7 @@ static inline void __init reserve_crashkernel_generic(char *cmdline,
>  struct crash_mem {
>  	unsigned int max_nr_ranges;
>  	unsigned int nr_ranges;
> -	struct range ranges[];
> +	struct range ranges[] __counted_by(max_nr_ranges);

This __counted_by() only makes sense when there's a obvious upper
boundary, max_nr_ranges in this case. This heavily depends and isn't
much in kernel? E.g struct swap_info_struct->avail_lists[]. Just
curious, not related to this patch though.

>  };
>  
>  extern int crash_exclude_mem_range(struct crash_mem *mem,
> -- 
> 2.34.1
> 


  reply	other threads:[~2023-09-23  0:47 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-22 17:52 [PATCH] kexec: Annotate struct crash_mem with __counted_by Kees Cook
2023-09-22 17:52 ` Kees Cook
2023-09-23  0:46 ` Baoquan He [this message]
2023-09-23  0:46   ` Baoquan He
2023-09-23  3:25   ` Kees Cook
2023-09-23  3:25     ` Kees Cook
2023-09-24  0:52     ` Baoquan He
2023-09-24  0:52       ` Baoquan He
2023-10-24 21:18 ` Kees Cook
2023-10-24 21:18   ` Kees Cook

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