From d4f86beacc21d538dc41e1fc75a22e084f547edf Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Thu, 2 Jul 2015 12:09:36 +0300 Subject: [PATCH] x86/kasan: Fix boot crash on AMD processors While populating zero shadow wrong bits in upper level page tables used. __PAGE_KERNEL_RO that was used for pgd/pud/pmd has _PAGE_BIT_GLOBAL set. Global bit is present only in the lowest level of the page translation hierarchy (ptes), and it should be zero in upper levels. This bug seems doesn't cause any troubles on Intel cpus, while on AMDs it cause kernel crash on boot. Use _KERNPG_TABLE bits for pgds/puds/pmds to fix this. Reported-by: Borislav Petkov Signed-off-by: Andrey Ryabinin Cc: # 4.0+ Cc: Alexander Popov Cc: Alexander Potapenko Cc: Andrey Konovalov Cc: Dmitry Vyukov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1435828178-10975-5-git-send-email-a.ryabinin@samsung.com Signed-off-by: Ingo Molnar --- arch/x86/mm/kasan_init_64.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c index 5d26642e4e8a..9a54dbe98064 100644 --- a/arch/x86/mm/kasan_init_64.c +++ b/arch/x86/mm/kasan_init_64.c @@ -85,7 +85,7 @@ static int __init zero_pmd_populate(pud_t *pud, unsigned long addr, while (IS_ALIGNED(addr, PMD_SIZE) && addr + PMD_SIZE <= end) { WARN_ON(!pmd_none(*pmd)); set_pmd(pmd, __pmd(__pa_nodebug(kasan_zero_pte) - | __PAGE_KERNEL_RO)); + | _KERNPG_TABLE)); addr += PMD_SIZE; pmd = pmd_offset(pud, addr); } @@ -111,7 +111,7 @@ static int __init zero_pud_populate(pgd_t *pgd, unsigned long addr, while (IS_ALIGNED(addr, PUD_SIZE) && addr + PUD_SIZE <= end) { WARN_ON(!pud_none(*pud)); set_pud(pud, __pud(__pa_nodebug(kasan_zero_pmd) - | __PAGE_KERNEL_RO)); + | _KERNPG_TABLE)); addr += PUD_SIZE; pud = pud_offset(pgd, addr); } @@ -136,7 +136,7 @@ static int __init zero_pgd_populate(unsigned long addr, unsigned long end) while (IS_ALIGNED(addr, PGDIR_SIZE) && addr + PGDIR_SIZE <= end) { WARN_ON(!pgd_none(*pgd)); set_pgd(pgd, __pgd(__pa_nodebug(kasan_zero_pud) - | __PAGE_KERNEL_RO)); + | _KERNPG_TABLE)); addr += PGDIR_SIZE; pgd = pgd_offset_k(addr); }