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| author |   Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2017-04-25 12:25:57 +0300 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2017-04-26 08:26:43 +0200 |
| commit | e6ab9c4d437764c7fb728d428dc9e717cdb183d0 (patch) | |
| tree | 4cae14dfd336fb180108154065811653dcfe23f3 /arch/x86/mm/init_64.c | |
| parent | Revert "x86/mm/gup: Switch GUP to the generic get_user_page_fast() implementation" (diff) | |
| download | linux-dev-e6ab9c4d437764c7fb728d428dc9e717cdb183d0.tar.xz linux-dev-e6ab9c4d437764c7fb728d428dc9e717cdb183d0.zip | |
x86/mm/64: Fix crash in remove_pagetable()
remove_pagetable() does page walk using p*d_page_vaddr() plus cast.
It's not canonical approach -- we usually use p*d_offset() for that.
It works fine as long as all page table levels are present. We broke the
invariant by introducing folded p4d page table level.
As result, remove_pagetable() interprets PMD as PUD and it leads to
crash:
BUG: unable to handle kernel paging request at ffff880300000000
IP: memchr_inv+0x60/0x110
PGD 317d067
P4D 317d067
PUD 3180067
PMD 33f102067
PTE 8000000300000060
Let's fix this by using p*d_offset() instead of p*d_page_vaddr() for
page walk.
Reported-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Fixes: f2a6a7050109 ("x86: Convert the rest of the code to support p4d_t")
Link: http://lkml.kernel.org/r/20170425092557.21852-1-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/mm/init_64.c')
| -rw-r--r-- | arch/x86/mm/init_64.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index a242139df8fe..745e5e183169 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -962,7 +962,7 @@ remove_pud_table(pud_t *pud_start, unsigned long addr, unsigned long end, continue; } - pmd_base = (pmd_t *)pud_page_vaddr(*pud); + pmd_base = pmd_offset(pud, 0); remove_pmd_table(pmd_base, addr, next, direct); free_pmd_table(pmd_base, pud); } @@ -988,7 +988,7 @@ remove_p4d_table(p4d_t *p4d_start, unsigned long addr, unsigned long end, BUILD_BUG_ON(p4d_large(*p4d)); - pud_base = (pud_t *)p4d_page_vaddr(*p4d); + pud_base = pud_offset(p4d, 0); remove_pud_table(pud_base, addr, next, direct); free_pud_table(pud_base, p4d); } @@ -1013,7 +1013,7 @@ remove_pagetable(unsigned long start, unsigned long end, bool direct) if (!pgd_present(*pgd)) continue; - p4d = (p4d_t *)pgd_page_vaddr(*pgd); + p4d = p4d_offset(pgd, 0); remove_p4d_table(p4d, addr, next, direct); } |