>Sorry for being late. I know there was some pre-existing discussion
>around that but I didn't have time to participate.
>
>On Mon 10-04-23 16:32:28, Jaewon Kim wrote:
>> @@ -350,6 +350,9 @@ static struct dma_buf *system_heap_allocate(struct dma_heap *heap,
>> struct page *page, *tmp_page;
>> int i, ret = -ENOMEM;
>>
>> + if (len / PAGE_SIZE > totalram_pages())
>> + return ERR_PTR(-ENOMEM);
>> +
>
>This is an antipattern imho. Check 7661809d493b ("mm: don't allow
>oversized kvmalloc() calls") how kvmalloc has dealt with a similar
Hello Thank you for the information.
I tried to search the macro of INT_MAX.
include/vdso/limits.h
#define INT_MAX ((int)(~0U >> 1))
AFAIK the dma-buf system heap user can request that huge size more than 2GB. So
I think totalram_pages() is better than INT_MAX in this case.
>issue. totalram_pages doesn't really tell you anything about incorrect
>users. You might be on a low memory system where the request size is
>sane normally, it just doesn't fit into memory on that particular
>machine.
Sorry maybe I'm not fully understand what you meant. User may requested
a huge size like 3GB on 2GB ram device. But I think that should be rejected
because it is bigger than the device ram size.
Jaewon Kim
>
>
>> buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
>> if (!buffer)
>> return ERR_PTR(-ENOMEM);
>> --
>> 2.17.1
>
>--
>Michal Hocko
>SUSE Labs
