linux-kernel - Re: [PATCH v2 01/11] kasan: unify static kasan_flag

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Message-ID: <aGKDhPBgDv2JjJZr@li-008a6a4c-3549-11b2-a85c-c5cc2836eea2.ibm.com>
Date: Mon, 30 Jun 2025 14:31:00 +0200
From: Alexander Gordeev <agordeev@...ux.ibm.com>
To: Sabyrzhan Tasbolatov <snovitoll@...il.com>
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Subject: Re: [PATCH v2 01/11] kasan: unify static kasan_flag_enabled across
 modes

On Thu, Jun 26, 2025 at 08:31:37PM +0500, Sabyrzhan Tasbolatov wrote:

Hi Sabyrzhan,

> diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
> index d54e89f8c3e..32c432df24a 100644
> --- a/mm/kasan/generic.c
> +++ b/mm/kasan/generic.c
> @@ -36,6 +36,17 @@
>  #include "kasan.h"
>  #include "../slab.h"
>  
> +/*
> + * Initialize Generic KASAN and enable runtime checks.
> + * This should be called from arch kasan_init() once shadow memory is ready.
> + */
> +void __init kasan_init_generic(void)
> +{
> +	static_branch_enable(&kasan_flag_enabled);

s390 crashes at this line, when the whole series is applied.

FWIW, it looks like kasan is called while its state is not yet finalized.
E.g. whether calling __asan_report_store4_noabort() before kasan_init_generic()
is expected?

 32e0a54:       c0 e5 fe a9 70 56       brasl   %r14,80eb00 <__asan_report_store4_noabort>
 32e0a5a:       c4 28 ff cb bb a3       lgrl    %r2,2c581a0 <_GLOBAL_OFFSET_TABLE_+0x70c0>
        sort_extable(__start_amode31_ex_table, __stop_amode31_ex_table);        
 32e0a60:       a5 ac 00 1c             llihh   %r10,28                         
        init_task.kasan_depth = 0;                                              
 32e0a64:       e3 40 2b c8 01 71       lay     %r4,7112(%r2)                   
 32e0a6a:       e5 4c 40 00 00 00       mvhi    0(%r4),0                        
        kasan_init_generic();                                                   
 32e0a70:       c0 e5 00 01 e7 3c       brasl   %r14,331d8e8 <kasan_init_generic>

> +	pr_info("KernelAddressSanitizer initialized (generic)\n");
> +}

Thanks!