From 57b78a62e7f23c4686fe54091cdc3d12e60d6513 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 3 Apr 2019 09:39:50 +0200 Subject: x86/uaccess, kasan: Fix KASAN vs SMAP KASAN inserts extra code for every LOAD/STORE emitted by te compiler. Much of this code is simple and safe to run with AC=1, however the kasan_report() function, called on error, is most certainly not safe to call with AC=1. Therefore wrap kasan_report() in user_access_{save,restore}; which for x86 SMAP, saves/restores EFLAGS and clears AC before calling the real function. Also ensure all the functions are without __fentry__ hook. The function tracer is also not safe. Signed-off-by: Peter Zijlstra (Intel) Cc: Borislav Petkov Cc: Dmitry Vyukov Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Ingo Molnar --- mm/kasan/Makefile | 3 +++ mm/kasan/common.c | 10 ++++++++++ mm/kasan/report.c | 3 +-- 3 files changed, 14 insertions(+), 2 deletions(-) (limited to 'mm/kasan') diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile index 5d1065efbd47..613dfe681e9f 100644 --- a/mm/kasan/Makefile +++ b/mm/kasan/Makefile @@ -2,11 +2,13 @@ KASAN_SANITIZE := n UBSAN_SANITIZE_common.o := n UBSAN_SANITIZE_generic.o := n +UBSAN_SANITIZE_generic_report.o := n UBSAN_SANITIZE_tags.o := n KCOV_INSTRUMENT := n CFLAGS_REMOVE_common.o = -pg CFLAGS_REMOVE_generic.o = -pg +CFLAGS_REMOVE_generic_report.o = -pg CFLAGS_REMOVE_tags.o = -pg # Function splitter causes unnecessary splits in __asan_load1/__asan_store1 @@ -14,6 +16,7 @@ CFLAGS_REMOVE_tags.o = -pg CFLAGS_common.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) CFLAGS_generic.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) +CFLAGS_generic_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) CFLAGS_tags.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) obj-$(CONFIG_KASAN) := common.o init.o report.o diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 80bbe62b16cd..09c586474511 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -36,6 +36,7 @@ #include #include #include +#include #include "kasan.h" #include "../slab.h" @@ -614,6 +615,15 @@ void kasan_free_shadow(const struct vm_struct *vm) vfree(kasan_mem_to_shadow(vm->addr)); } +extern void __kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip); + +void kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip) +{ + unsigned long flags = user_access_save(); + __kasan_report(addr, size, is_write, ip); + user_access_restore(flags); +} + #ifdef CONFIG_MEMORY_HOTPLUG static bool shadow_mapped(unsigned long addr) { diff --git a/mm/kasan/report.c b/mm/kasan/report.c index ca9418fe9232..0772820ad098 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -281,8 +281,7 @@ void kasan_report_invalid_free(void *object, unsigned long ip) end_report(&flags); } -void kasan_report(unsigned long addr, size_t size, - bool is_write, unsigned long ip) +void __kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip) { struct kasan_access_info info; void *tagged_addr; -- cgit v1.2.3-58-ga151