On Tue, Jan 18, 2022 at 10:53:54AM -0800, Yury Norov wrote: > vmap() takes struct page *pages as one of arguments, and user may provide > an invalid pointer, which would lead to DABT at address translation later. > Currently, kernel checks the pages against NULL. In my case, however, the > address was not NULL, and was big enough so that the hardware generated > Address Size Abort. > > Interestingly, this abort happens even if copy_from_kernel_nofault() is used, > which is quite inconvenient for debugging purposes. > > This patch adds an arch_vmap_page_valid() helper into vmap() path, so that > architectures may add arch-specific checks of the pointer passed into vmap. > > For arm64, if the page passed to vmap() corresponds to a physical address > greater than maximum possible value as described in TCR_EL1.IPS register, the > following table walk would generate Address Size Abort. Instead of creating > the invalid mapping, kernel will return ERANGE in such situation. This seems like a very elaborate way of spelling: pfn_valid(page_to_pfn(page)); which doesn't require any architecture hook. No?
