linux-kernel - Re: [PATCH v4 13/18] kasan: arm64: x86: Handle int3 for inline KASAN reports

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Message-ID: <31bac00f-7903-46f7-a5a0-1e8f5fd8b9ab@arm.com>
Date: Wed, 13 Aug 2025 15:49:15 +0100
From: Ada Couprie Diaz <ada.coupriediaz@....com>
To: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>
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 linux-kernel@...r.kernel.org, Ada Couprie Diaz <ada.coupriediaz@....com>
Subject: Re: [PATCH v4 13/18] kasan: arm64: x86: Handle int3 for inline KASAN
 reports

Hi,

On 12/08/2025 14:23, Maciej Wieczor-Retman wrote:
> [...]
>
> Make part of that hook - which decides whether to die or recover from a
> tag mismatch - arch independent to avoid duplicating a long comment on
> both x86 and arm64 architectures.
>
> Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>
> ---
> [...]
> diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
> index f528b6041f6a..b9bdabc14ad1 100644
> --- a/arch/arm64/kernel/traps.c
> +++ b/arch/arm64/kernel/traps.c
> @@ -1068,22 +1068,7 @@ int kasan_brk_handler(struct pt_regs *regs, unsigned long esr)
>   
>   	kasan_report(addr, size, write, pc);
>   
> -	/*
> -	 * The instrumentation allows to control whether we can proceed after
> -	 * a crash was detected. This is done by passing the -recover flag to
> -	 * the compiler. Disabling recovery allows to generate more compact
> -	 * code.
> -	 *
> -	 * Unfortunately disabling recovery doesn't work for the kernel right
> -	 * now. KASAN reporting is disabled in some contexts (for example when
> -	 * the allocator accesses slab object metadata; this is controlled by
> -	 * current->kasan_depth). All these accesses are detected by the tool,
> -	 * even though the reports for them are not printed.
> -	 *
> -	 * This is something that might be fixed at some point in the future.
> -	 */
> -	if (!recover)
> -		die("Oops - KASAN", regs, esr);
> +	kasan_inline_recover(recover, "Oops - KASAN", regs, esr);
It seems that `die` is missing as the last argument, otherwise
CONFIG_KASAN_SW_TAGS will not build on arm64.
With the fix, it builds fully without further issues.

Thanks,
Ada