From 88ae1de3aa1ad852d683202954e7c3acb96f0d38 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 2 Oct 2017 10:57:24 -0700 Subject: [PATCH 025/103] kaiser: kaiser_remove_mapping() move along the pgd 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 Signed-off-by: Greg Kroah-Hartman --- arch/x86/mm/kaiser.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/arch/x86/mm/kaiser.c b/arch/x86/mm/kaiser.c index fa1cb09..cc0950f 100644 --- a/arch/x86/mm/kaiser.c +++ b/arch/x86/mm/kaiser.c @@ -319,11 +319,13 @@ void kaiser_remove_mapping(unsigned long start, unsigned long size) 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); } } -- 2.7.4