Re: [PATCH] mm/mseal: Fix range_contains_unmapped() ignoring its mm argument

Re: [PATCH] mm/mseal: Fix range_contains_unmapped() ignoring its mm argument

[Hongfu Li]

Hi,

On 7/16/26 6:19 PM, Lorenzo Stoakes (ARM) wrote:
> On Thu, Jul 16, 2026 at 05:33:47PM +0800, Hongfu Li wrote:
>> From: Hongfu Li <lihongfu@kylinos.cn>
>>
>> range_contains_unmapped() accepts an explicit struct mm_struct *mm
>> argument, yet hardcodes current->mm inside VMA_ITERATOR(), ignoring
>> the passed address space.
>>
>> Its only caller do_mseal() currently passes current->mm, so the bug
>> does not manifest right now. However this mismatch between prototype
>> and implementation is a latent bug.
>>
>> Replace current->mm with the passed mm parameter to match the
>> function prototype.
>>
>> Fixes: 530e09096413 ("mm/mseal: simplify and rename VMA gap check")
> There's no point in a Fixes tag for something that's not a bug.
>
>> Signed-off-by: Hongfu Li <lihongfu@kylinos.cn>
>> ---
>>   mm/mseal.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/mm/mseal.c b/mm/mseal.c
>> index 9781647483d1..8d82e50900ba 100644
>> --- a/mm/mseal.c
>> +++ b/mm/mseal.c
>> @@ -41,7 +41,7 @@ static bool range_contains_unmapped(struct mm_struct *mm,
>>   {
>>   	struct vm_area_struct *vma;
>>   	unsigned long prev_end = start;
>> -	VMA_ITERATOR(vmi, current->mm, start);
>> +	VMA_ITERATOR(vmi, mm, start);
> We're never going to sensibly allow a remote mm here, and even suggesting so is
> problematic.
>
> Sorry but I think it's just easier if I send a broader cleanup patch to fix
> things up here more clearly.
Got it, thanks a lot for explaining the issue with remote mm. A unified 
broad cleanup patch works better for this code path. I will withdraw my 
patch and follow your series. Feel free to reach out if you need any 
testing help later.
Best regards,
Hongfu