powerpc/kasan: Fix shadow memory protection with CONFIG_KASAN_VMALLOC

With CONFIG_KASAN_VMALLOC, new page tables are created at the time
shadow memory for vmalloc area is unmapped. If some parts of the
page table still have entries to the zero page shadow memory, the
entries are wrongly marked RW.

With CONFIG_KASAN_VMALLOC, almost the entire kernel address space
is managed by KASAN. To make it simple, just create KASAN page tables
for the entire kernel space at kasan_init(). That doesn't use much
more space, and that's anyway already done for hash platforms.

Fixes: 3d4247fcc938 ("powerpc/32: Add support of KASAN_VMALLOC")
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/ef5248fc1f496c6b0dfdb59380f24968f25f75c5.1583513368.git.christophe.leroy@c-s.fr

diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c b/arch/powerpc/mm/kasan/kasan_init_32.c
index db5664dde5ff9d9d6a461eb1ed25a2d0f11e3d8e..d2bed3fcb7194ec065e107b71786797359fd8257 100644 (file)
--- a/arch/powerpc/mm/kasan/kasan_init_32.c
+++ b/arch/powerpc/mm/kasan/kasan_init_32.c
@@ -120,12 +120,6 @@ static void __init kasan_unmap_early_shadow_vmalloc(void)
        unsigned long k_cur;
        phys_addr_t pa = __pa(kasan_early_shadow_page);
 
-       if (!early_mmu_has_feature(MMU_FTR_HPTE_TABLE)) {
-               int ret = kasan_init_shadow_page_tables(k_start, k_end);
-
-               if (ret)
-                       panic("kasan: kasan_init_shadow_page_tables() failed");
-       }
        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);
                pte_t *ptep = pte_offset_kernel(pmd, k_cur);
@@ -143,7 +137,8 @@ void __init kasan_mmu_init(void)
        int ret;
        struct memblock_region *reg;
 
-       if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE)) {
+       if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE) ||
+           IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
                ret = kasan_init_shadow_page_tables(KASAN_SHADOW_START, KASAN_SHADOW_END);
 
                if (ret)