linux-kernel - Re: [PATCH] arm64: kprobes: check the return value of set_memory

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Message-ID: <41f0768f-e90b-49cd-80d5-8ad7ea43aac0@os.amperecomputing.com>
Date: Tue, 4 Nov 2025 07:57:12 -0800
From: Yang Shi <yang@...amperecomputing.com>
To: Punit Agrawal <punit.agrawal@....qualcomm.com>
Cc: catalin.marinas@....com, will@...nel.org, ryan.roberts@....com,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: kprobes: check the return value of
 set_memory_rox()



On 11/4/25 2:41 AM, Punit Agrawal wrote:
> Noticed a typo in the commit log while catching up with the rodata BBM
> optimizations.
>
> Yang Shi <yang@...amperecomputing.com> writes:
>
>> Since commit a166563e7ec3 ("arm64: mm: support large block mapping when
>> rodata=full"), __change_memory_common has more chance to fail due to
>> memory allocation fialure when splitting page table. So check the return
> Typo:               failure

Thank you for catching this. Will fix in v2.

Yang

>                    
>
>> value of set_memory_rox(), then bail out if it fails otherwise we may have
>> RW memory mapping for kprobes insn page.
>>
>> Fixes: 195a1b7d8388 ("arm64: kprobes: call set_memory_rox() for kprobe page")
>> Signed-off-by: Yang Shi <yang@...amperecomputing.com>
>> ---
>> I actually epxected 195a1b7d8388 ("arm64: kprobes: call set_memory_rox()
>> for kprobe page") can be merged in 6.17-rcX, so I just restored it to
>> before commit 10d5e97c1bf8 ("arm64: use PAGE_KERNEL_ROX directly in
>> alloc_insn_page"), however it turned out to be merged in 6.18-rc1 and it
>> is after commit a166563e7ec3 ("arm64: mm: support large block mapping when
>> rodata=full"). So I made the fix tag point to it.
>> And I don't think we need to backport this patch to pre-6.18.
>>
>>   arch/arm64/kernel/probes/kprobes.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
>> index 8ab6104a4883..43a0361a8bf0 100644
>> --- a/arch/arm64/kernel/probes/kprobes.c
>> +++ b/arch/arm64/kernel/probes/kprobes.c
>> @@ -49,7 +49,10 @@ void *alloc_insn_page(void)
>>   	addr = execmem_alloc(EXECMEM_KPROBES, PAGE_SIZE);
>>   	if (!addr)
>>   		return NULL;
>> -	set_memory_rox((unsigned long)addr, 1);
>> +	if (set_memory_rox((unsigned long)addr, 1)) {
>> +		execmem_free(addr);
>> +		return NULL;
>> +	}
>>   	return addr;
>>   }