Re: [PATCH v2 2/2] kasan, arm64: fix pointer tags in KASAN reports

[Catalin Marinas]

On Thu, Jan 14, 2021 at 08:33:57PM +0100, Andrey Konovalov wrote:
> As of the "arm64: expose FAR_EL1 tag bits in siginfo" patch, the address
> that is passed to report_tag_fault has pointer tags in the format of 0x0X,
> while KASAN uses 0xFX format (note the difference in the top 4 bits).
> 
> Fix up the pointer tag before calling kasan_report.
> 
> Link: https://linux-review.googlesource.com/id/I9ced973866036d8679e8f4ae325de547eb969649
> Fixes: dceec3ff7807 ("arm64: expose FAR_EL1 tag bits in siginfo")
> Fixes: 4291e9ee6189 ("kasan, arm64: print report from tag fault handler")
> Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> ---
>  arch/arm64/mm/fault.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
> index 3c40da479899..a218f6f2fdc8 100644
> --- a/arch/arm64/mm/fault.c
> +++ b/arch/arm64/mm/fault.c
> @@ -304,6 +304,8 @@ static void report_tag_fault(unsigned long addr, unsigned int esr,
>  {
>  	bool is_write  = ((esr & ESR_ELx_WNR) >> ESR_ELx_WNR_SHIFT) != 0;
>  
> +	/* The format of KASAN tags is 0xF<x>. */
> +	addr |= (0xF0UL << MTE_TAG_SHIFT);
>  	/*
>  	 * SAS bits aren't set for all faults reported in EL1, so we can't
>  	 * find out access size.

I already replied here but I don't see any change in v2:

https://lore.kernel.org/linux-arm-kernel/20210113165441.GC27045@gaia/

-- 
Catalin