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s390/kasan: avoid user access code instrumentation 

Kasan instrumentation adds "store" check for variables marked as
modified by inline assembly. With user pointers containing addresses
from another address space this produces false positives.

static inline unsigned long clear_user_xc(void __user *to, ...)
{
	asm volatile(
	...
	: "+a" (to) ...

User space access functions are wrapped by manually instrumented
functions in kasan common code, which should be sufficient to catch
errors. So, we just disable uaccess.o instrumentation altogether.

Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Vasily Gorbik 2017-11-17 17:20:28 +01:00 committed by Martin Schwidefsky
parent 7fef92ccad
commit b6cbe3e8bd
1 changed files with 4 additions and 0 deletions
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4
arch/s390/lib/Makefile
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@ -9,5 +9,9 @@ lib-$(CONFIG_SMP) += spinlock.o
lib-$(CONFIG_KPROBES) += probes.o
lib-$(CONFIG_UPROBES) += probes.o
# Instrumenting memory accesses to __user data (in different address space)
# produce false positives
KASAN_SANITIZE_uaccess.o := n
chkbss := mem.o
include $(srctree)/arch/s390/scripts/Makefile.chkbss