From 45ff3c55958542c3b76075d59741297b8cb31cbb Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Fri, 9 Aug 2019 14:58:09 +0000 Subject: [PATCH] powerpc/kasan: Fix parallel loading of modules. Parallel loading of modules may lead to bad setup of shadow page table entries. First, lets align modules so that two modules never share the same shadow page. Second, ensure that two modules cannot allocate two page tables for the same PMD entry at the same time. This is done by using init_mm.page_table_lock in the same way as __pte_alloc_kernel() Fixes: 2edb16efc899 ("powerpc/32: Add KASAN support") Cc: stable@vger.kernel.org # v5.2+ Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/c97284f912128cbc3f2fe09d68e90e65fb3e6026.1565361876.git.christophe.leroy@c-s.fr --- arch/powerpc/mm/kasan/kasan_init_32.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c b/arch/powerpc/mm/kasan/kasan_init_32.c index 74f4555..3282f8a 100644 --- a/arch/powerpc/mm/kasan/kasan_init_32.c +++ b/arch/powerpc/mm/kasan/kasan_init_32.c @@ -5,6 +5,7 @@ #include #include #include +#include #include #include #include @@ -46,7 +47,19 @@ static int __ref kasan_init_shadow_page_tables(unsigned long k_start, unsigned l kasan_populate_pte(new, PAGE_READONLY); else kasan_populate_pte(new, PAGE_KERNEL_RO); - pmd_populate_kernel(&init_mm, pmd, new); + + smp_wmb(); /* See comment in __pte_alloc */ + + spin_lock(&init_mm.page_table_lock); + /* Has another populated it ? */ + if (likely((void *)pmd_page_vaddr(*pmd) == kasan_early_shadow_pte)) { + pmd_populate_kernel(&init_mm, pmd, new); + new = NULL; + } + spin_unlock(&init_mm.page_table_lock); + + if (new && slab_is_available()) + pte_free_kernel(&init_mm, new); } return 0; } @@ -137,7 +150,11 @@ void __init kasan_init(void) #ifdef CONFIG_MODULES void *module_alloc(unsigned long size) { - void *base = vmalloc_exec(size); + void *base; + + base = __vmalloc_node_range(size, MODULE_ALIGN, VMALLOC_START, VMALLOC_END, + GFP_KERNEL, PAGE_KERNEL_EXEC, VM_FLUSH_RESET_PERMS, + NUMA_NO_NODE, __builtin_return_address(0)); if (!base) return NULL; -- 2.7.4