2021-01-22 14:46:41

by Andrey Konovalov

Subject: Re: [PATCH v7 3/4] kasan: Add report for async mode

On Fri, Jan 22, 2021 at 3:11 PM Vincenzo Frascino
<[email protected]> wrote:
>
> KASAN provides an asynchronous mode of execution.
>
> Add reporting functionality for this mode.
>
> Cc: Dmitry Vyukov <[email protected]>
> Cc: Andrey Ryabinin <[email protected]>
> Cc: Alexander Potapenko <[email protected]>
> Cc: Andrey Konovalov <[email protected]>
> Reviewed-by: Andrey Konovalov <[email protected]>
> Signed-off-by: Vincenzo Frascino <[email protected]>
> ---
> include/linux/kasan.h | 2 ++
> mm/kasan/report.c | 13 +++++++++++++
> 2 files changed, 15 insertions(+)
>
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index bb862d1f0e15..b0a1d9dfa85c 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -351,6 +351,8 @@ static inline void *kasan_reset_tag(const void *addr)
> bool kasan_report(unsigned long addr, size_t size,
> bool is_write, unsigned long ip);
>
> +void kasan_report_async(void);
> +
> #else /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */
>
> static inline void *kasan_reset_tag(const void *addr)
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index 234f35a84f19..1390da06a988 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -358,6 +358,19 @@ void kasan_report_invalid_free(void *object, unsigned long ip)
> end_report(&flags);
> }
>
> +#if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)

This looks wrong, CONFIG_KASAN_SW_TAGS doesn't use MTE, so this
function isn't needed for that mode.

Let's add an #ifdef CONFIG_KASAN_HW_TAGS section in
include/linux/kasan.h after the HW/SW one with kasan_report(). And
only leave CONFIG_KASAN_HW_TAGS in mm/kasan/report.c too.

> +void kasan_report_async(void)
> +{
> + unsigned long flags;
> +
> + start_report(&flags);
> + pr_err("BUG: KASAN: invalid-access\n");
> + pr_err("Asynchronous mode enabled: no access details available\n");
> + dump_stack();
> + end_report(&flags);
> +}
> +#endif /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */
> +
> static void __kasan_report(unsigned long addr, size_t size, bool is_write,
> unsigned long ip)
> {
> --
> 2.30.0
>

2021-01-22 15:38:25

by Vincenzo Frascino

Subject: Re: [PATCH v7 3/4] kasan: Add report for async mode

On 1/22/21 2:42 PM, Andrey Konovalov wrote:
> On Fri, Jan 22, 2021 at 3:11 PM Vincenzo Frascino
> <[email protected]> wrote:
>>
>> KASAN provides an asynchronous mode of execution.
>>
>> Add reporting functionality for this mode.
>>
>> Cc: Dmitry Vyukov <[email protected]>
>> Cc: Andrey Ryabinin <[email protected]>
>> Cc: Alexander Potapenko <[email protected]>
>> Cc: Andrey Konovalov <[email protected]>
>> Reviewed-by: Andrey Konovalov <[email protected]>
>> Signed-off-by: Vincenzo Frascino <[email protected]>
>> ---
>> include/linux/kasan.h | 2 ++
>> mm/kasan/report.c | 13 +++++++++++++
>> 2 files changed, 15 insertions(+)
>>
>> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
>> index bb862d1f0e15..b0a1d9dfa85c 100644
>> --- a/include/linux/kasan.h
>> +++ b/include/linux/kasan.h
>> @@ -351,6 +351,8 @@ static inline void *kasan_reset_tag(const void *addr)
>> bool kasan_report(unsigned long addr, size_t size,
>> bool is_write, unsigned long ip);
>>
>> +void kasan_report_async(void);
>> +
>> #else /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */
>>
>> static inline void *kasan_reset_tag(const void *addr)
>> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
>> index 234f35a84f19..1390da06a988 100644
>> --- a/mm/kasan/report.c
>> +++ b/mm/kasan/report.c
>> @@ -358,6 +358,19 @@ void kasan_report_invalid_free(void *object, unsigned long ip)
>> end_report(&flags);
>> }
>>
>> +#if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
>
> This looks wrong, CONFIG_KASAN_SW_TAGS doesn't use MTE, so this
> function isn't needed for that mode.
>

It is true, I will fix in v8.

> Let's add an #ifdef CONFIG_KASAN_HW_TAGS section in
> include/linux/kasan.h after the HW/SW one with kasan_report(). And
> only leave CONFIG_KASAN_HW_TAGS in mm/kasan/report.c too.
>
>> +void kasan_report_async(void)
>> +{
>> + unsigned long flags;
>> +
>> + start_report(&flags);
>> + pr_err("BUG: KASAN: invalid-access\n");
>> + pr_err("Asynchronous mode enabled: no access details available\n");
>> + dump_stack();
>> + end_report(&flags);
>> +}
>> +#endif /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */
>> +
>> static void __kasan_report(unsigned long addr, size_t size, bool is_write,
>> unsigned long ip)
>> {
>> --
>> 2.30.0
>>

--
Regards,
Vincenzo