| From foo@baz Wed Jan 3 18:58:12 CET 2018 |
| From: Hugh Dickins <hughd@google.com> |
| Date: Mon, 2 Oct 2017 10:57:24 -0700 |
| Subject: kaiser: kaiser_remove_mapping() move along the pgd |
| |
| From: Hugh Dickins <hughd@google.com> |
| |
| |
| When removing the bogus comment from kaiser_remove_mapping(), |
| I really ought to have checked the extent of its bogosity: as |
| Neel points out, there is nothing to stop unmap_pud_range_nofree() |
| from continuing beyond the end of a pud (and starting in the wrong |
| position on the next). |
| |
| Fix kaiser_remove_mapping() to constrain the extent and advance pgd |
| pointer correctly: use pgd_addr_end() macro as used throughout base |
| mm (but don't assume page-rounded start and size in this case). |
| |
| But this bug was very unlikely to trigger in this backport: since |
| any buddy allocation is contained within a single pud extent, and |
| we are not using vmapped stacks (and are only mapping one page of |
| stack anyway): the only way to hit this bug here would be when |
| freeing a large modified ldt. |
| |
| Signed-off-by: Hugh Dickins <hughd@google.com> |
| Acked-by: Jiri Kosina <jkosina@suse.cz> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| arch/x86/mm/kaiser.c | 10 ++++++---- |
| 1 file changed, 6 insertions(+), 4 deletions(-) |
| |
| --- a/arch/x86/mm/kaiser.c |
| +++ b/arch/x86/mm/kaiser.c |
| @@ -297,11 +297,13 @@ void kaiser_remove_mapping(unsigned long |
| extern void unmap_pud_range_nofree(pgd_t *pgd, |
| unsigned long start, unsigned long end); |
| unsigned long end = start + size; |
| - unsigned long addr; |
| + unsigned long addr, next; |
| + pgd_t *pgd; |
| |
| - for (addr = start; addr < end; addr += PGDIR_SIZE) { |
| - pgd_t *pgd = native_get_shadow_pgd(pgd_offset_k(addr)); |
| - unmap_pud_range_nofree(pgd, addr, end); |
| + pgd = native_get_shadow_pgd(pgd_offset_k(start)); |
| + for (addr = start; addr < end; pgd++, addr = next) { |
| + next = pgd_addr_end(addr, end); |
| + unmap_pud_range_nofree(pgd, addr, next); |
| } |
| } |
| |