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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