Commit-ID: d86bbf61c8bef9115145b29f928316637a29f546
Gitweb: https://git.kernel.org/tip/d86bbf61c8bef9115145b29f928316637a29f546
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Wed, 3 Apr 2019 09:40:16 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 3 Apr 2019 09:40:16 +0200
x86/uaccess, ubsan: Fix UBSAN vs. SMAP
UBSAN can insert extra code in random locations; including AC=1
sections. Typically this code is not safe and needs wrapping.
So far, only __ubsan_handle_type_mismatch* have been observed in AC=1
sections and therefore only those are annotated.
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>
---
lib/Makefile | 1 +
lib/ubsan.c | 4 ++++
2 files changed, 5 insertions(+)
diff --git a/lib/Makefile b/lib/Makefile
index 3b08673e8881..c4563e7c47ba 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -268,6 +268,7 @@ obj-$(CONFIG_UCS2_STRING) += ucs2_string.o
obj-$(CONFIG_UBSAN) += ubsan.o
UBSAN_SANITIZE_ubsan.o := n
+CFLAGS_ubsan.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
obj-$(CONFIG_SBITMAP) += sbitmap.o
diff --git a/lib/ubsan.c b/lib/ubsan.c
index e4162f59a81c..c8e905bfb627 100644
--- a/lib/ubsan.c
+++ b/lib/ubsan.c
@@ -17,6 +17,7 @@
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/sched.h>
+#include <linux/uaccess.h>
#include "ubsan.h"
@@ -313,6 +314,7 @@ static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
unsigned long ptr)
{
+ unsigned long flags = user_access_save();
if (!ptr)
handle_null_ptr_deref(data);
@@ -320,6 +322,8 @@ static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
handle_misaligned_access(data, ptr);
else
handle_object_size_mismatch(data, ptr);
+
+ user_access_restore(flags);
}
void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
|