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x86/mm: Prevent kernel Oops in PTDUMP code with HIGHPTE=y

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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: fe770bf031 ('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
This commit is contained in:
Joerg Roedel 2018-04-17 15:27:16 +02:00 committed by Thomas Gleixner
parent 1340ccfa9a
commit d6ef1f194b
1 changed files with 6 additions and 5 deletions
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11
arch/x86/mm/dump_pagetables.c
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@ -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