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authorPeter Zijlstra <peterz@infradead.org>2019-04-03 09:40:16 +0200
committerIngo Molnar <mingo@kernel.org>2019-04-03 11:02:24 +0200
commitd08965a27e84ca090b504844d50c24fc98587b11 (patch)
treec89c3883246d70a6e9ef5bc16200c763c8dc0071
parent57b78a62e7f23c4686fe54091cdc3d12e60d6513 (diff)
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@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--lib/Makefile1
-rw-r--r--lib/ubsan.c4
2 files changed, 5 insertions, 0 deletions
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,