The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From d6ef1f194b7569af8b8397876dc9ab07649d63cb Mon Sep 17 00:00:00 2001
From: Joerg Roedel jroedel@suse.de Date: Tue, 17 Apr 2018 15:27:16 +0200 Subject: [PATCH] x86/mm: Prevent kernel Oops in PTDUMP code with HIGHPTE=y
The walk_pte_level() function just uses __va to get the virtual address of the PTE page, but that breaks when the PTE page is not in the direct mapping with HIGHPTE=y.
The result is an unhandled kernel paging request at some random address when accessing the current_kernel or current_user file.
Use the correct API to access PTE pages.
Fixes: fe770bf0310d ('x86: clean up the page table dumper and add 32-bit support') Signed-off-by: Joerg Roedel jroedel@suse.de Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: stable@vger.kernel.org Cc: jgross@suse.com Cc: JBeulich@suse.com Cc: hpa@zytor.com Cc: aryabinin@virtuozzo.com Cc: kirill.shutemov@linux.intel.com Link: https://lkml.kernel.org/r/1523971636-4137-1-git-send-email-joro@8bytes.org
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c index 62a7e9f65dec..cc7ff5957194 100644 --- a/arch/x86/mm/dump_pagetables.c +++ b/arch/x86/mm/dump_pagetables.c @@ -18,6 +18,7 @@ #include <linux/init.h> #include <linux/sched.h> #include <linux/seq_file.h> +#include <linux/highmem.h>
#include <asm/pgtable.h>
@@ -334,16 +335,16 @@ static void walk_pte_level(struct seq_file *m, struct pg_state *st, pmd_t addr, pgprotval_t eff_in, unsigned long P) { int i; - pte_t *start; + pte_t *pte; pgprotval_t prot, eff;
- start = (pte_t *)pmd_page_vaddr(addr); for (i = 0; i < PTRS_PER_PTE; i++) { - prot = pte_flags(*start); - eff = effective_prot(eff_in, prot); st->current_address = normalize_addr(P + i * PTE_LEVEL_MULT); + pte = pte_offset_map(&addr, st->current_address); + prot = pte_flags(*pte); + eff = effective_prot(eff_in, prot); note_page(m, st, __pgprot(prot), eff, 5); - start++; + pte_unmap(pte); } } #ifdef CONFIG_KASAN