FAILED: patch "[PATCH] kasan: don't emit builtin calls when sanitization is off" failed to apply to 4.9-stable tree

PATCH [email protected] 1 participant 1 message Feb 15, 2018

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Stable branch Kbuild KASAN

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2018-02-15 08:09 UTC #0 lore raw

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

Quoted 1 line

From 0e410e158e5baa1300bdf678cea4f4e0cf9d8b94 Mon Sep 17 00:00:00 2001

From: Andrey Konovalov <[email protected]>
Date: Tue, 6 Feb 2018 15:36:00 -0800
Subject: [PATCH] kasan: don't emit builtin calls when sanitization is off

With KASAN enabled the kernel has two different memset() functions, one with KASAN checks (memset) and one without (__memset). KASAN uses some macro tricks to use the proper version where required. For example memset() calls in mm/slub.c are without KASAN checks, since they operate on poisoned slab object metadata.

The issue is that clang emits memset() calls even when there is no memset() in the source code. They get linked with improper memset() implementation and the kernel fails to boot due to a huge amount of KASAN reports during early boot stages.

The solution is to add -fno-builtin flag for files with KASAN_SANITIZE := n marker.

Link http://lkml.kernel.org/r/8ffecfffe04088c52c42b92739c2bd8a0bcb3f5e.1516384594.git.andreyknvl@google.com open here

Signed-off-by Andrey Konovalov <[email protected]>

Acked-by Nick Desaulniers <[email protected]>

Cc Masahiro Yamada <[email protected]>

Cc Michal Marek <[email protected]>

Cc Andrey Ryabinin <[email protected]>

Cc Alexander Potapenko <[email protected]>

Cc Dmitry Vyukov <[email protected]>

Cc <[email protected]>

Signed-off-by Andrew Morton <[email protected]>

Signed-off-by Linus Torvalds <[email protected]>

Makefile +2 -1

index 11aff0f9e105..0d49ff4022fb 100644
@@ -434,7 +434,8 @@ export MAKE LEX YACC AWK GENKSYMS INSTALLKERNEL PERL PYTHON UTS_MACHINE
 export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS
 
 export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS LDFLAGS
-export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE CFLAGS_KASAN CFLAGS_UBSAN
+export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE
+export CFLAGS_KASAN CFLAGS_KASAN_NOSANITIZE CFLAGS_UBSAN
 export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
 export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE
 export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL

scripts/Makefile.kasan +3 -0

index 1ce7115aa499..94c9e65cc83a 100644
@@ -31,4 +31,7 @@ else
 endif
 
 CFLAGS_KASAN += $(call cc-option, -fsanitize-address-use-after-scope)
+
+CFLAGS_KASAN_NOSANITIZE := -fno-builtin
+
 endif

scripts/Makefile.lib +1 -1

index 5fdc1a19b02c..5589bae34af6 100644
@@ -121,7 +121,7 @@ endif
 ifeq ($(CONFIG_KASAN),y)
 _c_flags += $(if $(patsubst n%,, \
 		$(KASAN_SANITIZE_$(basetarget).o)$(KASAN_SANITIZE)y), \
-		$(CFLAGS_KASAN))
+		$(CFLAGS_KASAN), $(CFLAGS_KASAN_NOSANITIZE))
 endif
 
 ifeq ($(CONFIG_UBSAN),y)