diff mbox series

[v2] vmap(): don't allow invalid pages

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

Commit Message

Yury Norov Jan. 19, 2022, 1:21 a.m. UTC
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(+)

Comments

Andrew Morton Jan. 26, 2022, 2:25 a.m. UTC | #1
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.
Yury Norov Jan. 26, 2022, 2:29 a.m. UTC | #2
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 mbox series

Patch

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);