powerpc/kasan: fix parallele loading of modules.
diff mbox series

Message ID c97284f912128cbc3f2fe09d68e90e65fb3e6026.1565361876.git.christophe.leroy@c-s.fr
State Accepted
Commit 45ff3c55958542c3b76075d59741297b8cb31cbb
Headers show
Series
  • powerpc/kasan: fix parallele loading of modules.
Related show

Checks

Context Check Description
snowpatch_ozlabs/checkpatch success total: 0 errors, 0 warnings, 0 checks, 39 lines checked
snowpatch_ozlabs/build-pmac32 success Build succeeded
snowpatch_ozlabs/build-ppc64e success Build succeeded
snowpatch_ozlabs/build-ppc64be success Build succeeded
snowpatch_ozlabs/build-ppc64le success Build succeeded
snowpatch_ozlabs/apply_patch success Successfully applied on branch next (f3365d1a959d5c6527efe3d38276acc9b58e3f3f)

Commit Message

christophe leroy Aug. 9, 2019, 2:58 p.m. UTC
Parallele 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
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/mm/kasan/kasan_init_32.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

Comments

Michael Ellerman Aug. 22, 2019, 1:08 p.m. UTC | #1
On Fri, 2019-08-09 at 14:58:09 UTC, Christophe Leroy wrote:
> Parallele 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
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/45ff3c55958542c3b76075d59741297b8cb31cbb

cheers

Patch
diff mbox series

diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c b/arch/powerpc/mm/kasan/kasan_init_32.c
index 99eac3fab83c..802387b231ad 100644
--- a/arch/powerpc/mm/kasan/kasan_init_32.c
+++ b/arch/powerpc/mm/kasan/kasan_init_32.c
@@ -5,6 +5,7 @@ 
 #include <linux/kasan.h>
 #include <linux/printk.h>
 #include <linux/memblock.h>
+#include <linux/moduleloader.h>
 #include <linux/sched/task.h>
 #include <linux/vmalloc.h>
 #include <asm/pgalloc.h>
@@ -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;