linux-kernel - Re: [PATCH] kasan: distinguish kasan report from generic BUG()

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Date:   Wed, 24 Nov 2021 19:04:02 +0100
From:   Jiri Slaby <jirislaby@...nel.org>
To:     Jiri Kosina <jikos@...nel.org>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Alexander Potapenko <glider@...gle.com>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     kasan-dev@...glegroups.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kasan: distinguish kasan report from generic BUG()

On 24. 11. 21, 18:41, Jiri Kosina wrote:
> From: Jiri Kosina <jkosina@...e.cz>
> 
> The typical KASAN report always begins with
> 
> 	BUG: KASAN: ....
> 
> in kernel log. That 'BUG:' prefix creates a false impression that it's an
> actual BUG() codepath being executed, and as such things like
> 'panic_on_oops' etc. would work on it as expected; but that's obviously
> not the case.
> 
> Switch the order of prefixes to make this distinction clear and avoid
> confusion.

Thinking about it more in the scope of panic_on_oops above: wouldn't it 
make more sense to emit "KASAN: WARNING:" instead? All that provided the 
fact the code explicitly does "if (panic_on_warn) { panic(); }"?

> Signed-off-by: Jiri Kosina <jkosina@...e.cz>
> ---
>   mm/kasan/report.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index 0bc10f452f7e..ead714c844e9 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -86,7 +86,7 @@ __setup("kasan_multi_shot", kasan_set_multi_shot);
>   
>   static void print_error_description(struct kasan_access_info *info)
>   {
> -	pr_err("BUG: KASAN: %s in %pS\n",
> +	pr_err("KASAN: BUG: %s in %pS\n",
>   		kasan_get_bug_type(info), (void *)info->ip);
>   	if (info->access_size)
>   		pr_err("%s of size %zu at addr %px by task %s/%d\n",
> @@ -366,7 +366,7 @@ void kasan_report_invalid_free(void *object, unsigned long ip)
>   #endif /* IS_ENABLED(CONFIG_KUNIT) */
>   
>   	start_report(&flags);
> -	pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", (void *)ip);
> +	pr_err("KASAN: BUG: double-free or invalid-free in %pS\n", (void *)ip);
>   	kasan_print_tags(tag, object);
>   	pr_err("\n");
>   	print_address_description(object, tag);
> @@ -386,7 +386,7 @@ void kasan_report_async(void)
>   #endif /* IS_ENABLED(CONFIG_KUNIT) */
>   
>   	start_report(&flags);
> -	pr_err("BUG: KASAN: invalid-access\n");
> +	pr_err("KASAN: BUG: invalid-access\n");
>   	pr_err("Asynchronous mode enabled: no access details available\n");
>   	pr_err("\n");
>   	dump_stack_lvl(KERN_ERR);
> 
> 


-- 
js
suse labs