[PATCH 5.3 031/148] powerpc/kasan: Fix shadow area set up for modules.

From: Greg Kroah-Hartman
Date: Thu Oct 10 2019 - 05:01:40 EST

From: Christophe Leroy <christophe.leroy@xxxxxx>

commit 663c0c9496a69f80011205ba3194049bcafd681d upstream.

When loading modules, from time to time an Oops is encountered during
the init of shadow area for globals. This is due to the last page not
always being mapped depending on the exact distance between the start
and the end of the shadow area and the alignment with the page

Fix this by aligning the starting address with the page address.

Fixes: 2edb16efc899 ("powerpc/32: Add KASAN support")
Cc: stable@xxxxxxxxxxxxxxx # v5.2+
Reported-by: Erhard F. <erhard_f@xxxxxxxxxxx>
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/4f887e9b77d0d725cbb52035c7ece485c1c5fc14.1565361881.git.christophe.leroy@xxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

arch/powerpc/mm/kasan/kasan_init_32.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/powerpc/mm/kasan/kasan_init_32.c
+++ b/arch/powerpc/mm/kasan/kasan_init_32.c
@@ -87,7 +87,7 @@ static int __ref kasan_init_region(void
if (!slab_is_available())
block = memblock_alloc(k_end - k_start, PAGE_SIZE);

- for (k_cur = k_start; k_cur < k_end; k_cur += PAGE_SIZE) {
+ for (k_cur = k_start & PAGE_MASK; k_cur < k_end; k_cur += PAGE_SIZE) {
pmd_t *pmd = pmd_offset(pud_offset(pgd_offset_k(k_cur), k_cur), k_cur);
void *va = block ? block + k_cur - k_start : kasan_get_one_page();
pte_t pte = pfn_pte(PHYS_PFN(__pa(va)), PAGE_KERNEL);