The patch below does not apply to the 4.4-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@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From d6ef1f194b7569af8b8397876dc9ab07649d63cb Mon Sep 17 00:00:00 2001
From: Joerg Roedel <jroedel@xxxxxxx>
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@xxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Cc: jgross@xxxxxxxx
Cc: JBeulich@xxxxxxxx
Cc: hpa@xxxxxxxxx
Cc: aryabinin@xxxxxxxxxxxxx
Cc: kirill.shutemov@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/1523971636-4137-1-git-send-email-joro@xxxxxxxxxx
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