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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>
hifive-unleashed-5.2
Peter Zijlstra 2019-04-03 09:40:16 +02:00 committed by Ingo Molnar
parent 57b78a62e7
commit d08965a27e
2 changed files with 5 additions and 0 deletions
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1
lib/Makefile
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@ -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

4
lib/ubsan.c
View File

@ -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,