Commit-ID: 3799e04b5da3a30ec184c8d5ed760dd3aeb9ac6e
Gitweb: https://git.kernel.org/tip/3799e04b5da3a30ec184c8d5ed760dd3aeb9ac6e
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Wed, 3 Apr 2019 09:39:50 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 3 Apr 2019 09:39:50 +0200
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) <peterz@xxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
mm/kasan/Makefile | 3 +++
mm/kasan/common.c | 10 ++++++++++
mm/kasan/report.c | 3 +--
3 files changed, 14 insertions(+), 2 deletions(-)
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 <linux/types.h>
#include <linux/vmalloc.h>
#include <linux/bug.h>
+#include <linux/uaccess.h>
#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;
|