[llvm-dev] [compiler-rt] Use of ESR context in AArch64 sigframe

[Andrey Ryabinin via llvm-dev]

On 03/06/2018 08:58 PM, Will Deacon wrote:
> Hi all,
> 
> As part of some recent work to harden the Kernel Address Space Layout
> Randomisation (KASLR) implementation in arm64 Linux, I've proposed a
> patch for the kernel which omits the ESR context from the signal frame
> if the faulting virtual address is outside the range of addresses which
> can be mapped by userspace.
> 
> http://lists.infradead.org/pipermail/linux-arm-kernel/2018-March/563837.html
> 
> Looking around, it seems that AddressSanitizer is using this information
> in compiler-rt in order to distinguish the faulting access type between
> READ, WRITE or UNKNOWN. With this change, all attempted accesses to kernel
> memory from userspace will be reported as UNKNOWN.
> 
> Is this likely to cause a problem?

I guess this shouldn't be a bid deal.
AFAICS compiler-rt uses this information only in diagnostic message.


> Many thanks,
> 
> Will
>