Re: [PATCH -next] arm64/ptrace: Fix stack-out-of-bounds read in regs_get_kernel_stack_nth()

[Tengda Wu]

On 2025/6/13 0:33, Will Deacon wrote:
> On Wed, Jun 04, 2025 at 12:55:33AM +0000, Tengda Wu wrote:
>> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
>> index f79b0d5f71ac..fe3f7e554d14 100644
>> --- a/arch/arm64/kernel/ptrace.c
>> +++ b/arch/arm64/kernel/ptrace.c
>> @@ -141,7 +141,7 @@ unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n)
>>  
>>  	addr += n;
>>  	if (regs_within_kernel_stack(regs, (unsigned long)addr))
>> -		return *addr;
>> +		return READ_ONCE_NOCHECK(addr);
> 
> I think this should be '*addr', but that makes me wonder wtf s390 is
> doing...
> 
> Will

Sorry, I just received this email as there have been some issues
with my mailbox recently. I was about to send the v2 version with
the '*' mark, but I found out you have already fixed and applied
it to the linux-next. Thank you for your tolerance.

Tengda