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SubjectRe: [PATCH V2 04/10] kasan: Don't use kasan shadow pointer in generic functions
From
2015-08-26 11:54 GMT+03:00 Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>:
>
> Missed to cherry-pick the updated version of this patch, before sending
> the series out.
>
> commit aeb324e09d95c189eda4ce03790da94b535d1dfc
> Author: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> Date: Fri Aug 14 12:28:58 2015 +0530
>
> kasan: Don't use kasan shadow pointer in generic functions
>
> We can't use generic functions like print_hex_dump to access kasan
> shadow region. This require us to setup another kasan shadow region
> for the address passed (kasan shadow address). Most architecture won't
> be able to do that. Hence make a copy of the shadow region row and
> pass that to generic functions.
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index d19d01823a68..60fdb0413f3b 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -166,14 +166,20 @@ static void print_shadow_for_address(const void *addr)
> for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) {
> const void *kaddr = kasan_shadow_to_mem(shadow_row);
> char buffer[4 + (BITS_PER_LONG/8)*2];
> + char shadow_buf[SHADOW_BYTES_PER_ROW];
>
> snprintf(buffer, sizeof(buffer),
> (i == 0) ? ">%p: " : " %p: ", kaddr);
> -
> + /*
> + * We should not pass a shadow pointer to generic
> + * function, because generic functions may try to
> + * kasan mapping for the passed address.

may try to *access* kasan mapping?

> + */
> + memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW);
> kasan_disable_current();
> print_hex_dump(KERN_ERR, buffer,
> DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
> - shadow_row, SHADOW_BYTES_PER_ROW, 0);
> + shadow_buf, SHADOW_BYTES_PER_ROW, 0);
> kasan_enable_current();
>
> if (row_is_guilty(shadow_row, shadow))
>


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