| Message ID | 20220119012109.551931-1-yury.norov@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] vmap(): don't allow invalid pages | expand |
On Tue, 18 Jan 2022 17:21:09 -0800 Yury Norov <yury.norov@gmail.com> wrote: > vmap() takes struct page *pages as one of arguments, and user may provide > an invalid pointer which would lead to data abort at address translation > later. Does "user" mean userspace code? If so, please tell us much more about the means by which userspace can trigger this problem.
On Tue, Jan 25, 2022 at 6:25 PM Andrew Morton <akpm@linux-foundation.org> wrote: > > On Tue, 18 Jan 2022 17:21:09 -0800 Yury Norov <yury.norov@gmail.com> wrote: > > > vmap() takes struct page *pages as one of arguments, and user may provide > > an invalid pointer which would lead to data abort at address translation > > later. > > Does "user" mean userspace code? > > If so, please tell us much more about the means by which userspace can > trigger this problem. User means user of vmap() API. The discussion is here: https://lore.kernel.org/linux-mm/20220118235244.540103-1-yury.norov@gmail.com/ I'll send v3 soon with more details in the patch description.
diff --git a/mm/vmalloc.c b/mm/vmalloc.c index d2a00ad4e1dd..a4134ee56b10 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -477,6 +477,8 @@ static int vmap_pages_pte_range(pmd_t *pmd, unsigned long addr, return -EBUSY; if (WARN_ON(!page)) return -ENOMEM; + if (WARN_ON(!pfn_valid(page_to_pfn(page)))) + return -EINVAL; set_pte_at(&init_mm, addr, pte, mk_pte(page, prot)); (*nr)++; } while (pte++, addr += PAGE_SIZE, addr != end);
vmap() takes struct page *pages as one of arguments, and user may provide an invalid pointer which would lead to data abort 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 on arm64. Interestingly, this abort happens even if copy_from_kernel_nofault() is used, which is quite inconvenient for debugging purposes. This patch adds a pfn_valid() check into vmap() path, so that invalid mapping will not be created. RFC: https://lkml.org/lkml/2022/1/18/815 v1: https://lkml.org/lkml/2022/1/18/1026 v2: Patch description changed. Suggested-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Yury Norov <yury.norov@gmail.com> --- mm/vmalloc.c | 2 ++ 1 file changed, 2 insertions(+)