From eafb149ed73a8bb8359c0ce027b98acd4e95b070 Mon Sep 17 00:00:00 2001 From: Daniel Axtens Date: Sat, 30 Nov 2019 17:54:57 -0800 Subject: fork: support VMAP_STACK with KASAN_VMALLOC Supporting VMAP_STACK with KASAN_VMALLOC is straightforward: - clear the shadow region of vmapped stacks when swapping them in - tweak Kconfig to allow VMAP_STACK to be turned on with KASAN Link: http://lkml.kernel.org/r/20191031093909.9228-4-dja@axtens.net Signed-off-by: Daniel Axtens Reviewed-by: Dmitry Vyukov Reviewed-by: Andrey Ryabinin Cc: Alexander Potapenko Cc: Christophe Leroy Cc: Mark Rutland Cc: Vasily Gorbik Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/Kconfig | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'arch/Kconfig') diff --git a/arch/Kconfig b/arch/Kconfig index 17c42bc36321..ec07f9ba1152 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -843,16 +843,17 @@ config HAVE_ARCH_VMAP_STACK config VMAP_STACK default y bool "Use a virtually-mapped stack" - depends on HAVE_ARCH_VMAP_STACK && !KASAN + depends on HAVE_ARCH_VMAP_STACK + depends on !KASAN || KASAN_VMALLOC ---help--- Enable this if you want the use virtually-mapped kernel stacks with guard pages. This causes kernel stack overflows to be caught immediately rather than causing difficult-to-diagnose corruption. - This is presently incompatible with KASAN because KASAN expects - the stack to map directly to the KASAN shadow map using a formula - that is incorrect if the stack is in vmalloc space. + To use this with KASAN, the architecture must support backing + virtual mappings with real shadow memory, and KASAN_VMALLOC must + be enabled. config ARCH_OPTIONAL_KERNEL_RWX def_bool n -- cgit v1.2.3