+ ubsan-build-ubsanc-more-conservatively.patch added to -mm tree

[akpm@linux-foundation.org]

The patch titled
     Subject: ubsan: build ubsan.c more conservatively
has been added to the -mm tree.  Its filename is
     ubsan-build-ubsanc-more-conservatively.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/ubsan-build-ubsanc-more-conservatively.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/ubsan-build-ubsanc-more-conservatively.patch

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------------------------------------------------------
From: Arnd Bergmann <arnd@arndb.de>
Subject: ubsan: build ubsan.c more conservatively

objtool points out several conditions that it does not like, depending on
the combination with other configuration options and compiler variants:

stack protector:
lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch()+0xbf: call to __stack_chk_fail() with UACCESS enabled
lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch_v1()+0xbe: call to __stack_chk_fail() with UACCESS enabled

stackleak plugin:
lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch()+0x4a: call to stackleak_track_stack() with UACCESS enabled
lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch_v1()+0x4a: call to stackleak_track_stack() with UACCESS enabled

kasan:
lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch()+0x25: call to memcpy() with UACCESS enabled
lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch_v1()+0x25: call to memcpy() with UACCESS enabled

The stackleak and kasan options just need to be disabled for this file as
we do for other files already.  For the stack protector, we already
attempt to disable it, but this fails on clang because the check is mixed
with the gcc specific -fno-conserve-stack option.  According to Andrey
Ryabinin, that option is not even needed, dropping it here fixes the
stackprotector issue.

Link: http://lkml.kernel.org/r/20190722125139.1335385-1-arnd@arndb.de
Link: https://lore.kernel.org/lkml/20190617123109.667090-1-arnd@arndb.de/t/
Link: https://lore.kernel.org/lkml/20190722091050.2188664-1-arnd@arndb.de/t/
Fixes: d08965a27e84 ("x86/uaccess, ubsan: Fix UBSAN vs. SMAP")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/Makefile |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/lib/Makefile~ubsan-build-ubsanc-more-conservatively
+++ a/lib/Makefile
@@ -279,7 +279,8 @@ obj-$(CONFIG_UCS2_STRING) += ucs2_string
 obj-$(CONFIG_UBSAN) += ubsan.o
 
 UBSAN_SANITIZE_ubsan.o := n
-CFLAGS_ubsan.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
+KASAN_SANITIZE_ubsan.o := n
+CFLAGS_ubsan.o := $(call cc-option, -fno-stack-protector) $(DISABLE_STACKLEAK_PLUGIN)
 
 obj-$(CONFIG_SBITMAP) += sbitmap.o
 
_

Patches currently in -mm which might be from arnd@arndb.de are

kasan-remove-clang-version-check-for-kasan_stack.patch
ubsan-build-ubsanc-more-conservatively.patch
mm-sparse-fix-memory-leak-of-sparsemap_buf-in-aliged-memory-fix.patch