[v2] ubsan: build ubsan.c more conservatively
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Message ID 20190722125139.1335385-1-arnd@arndb.de
State In Next
Commit a00f38e836fd52ae250756a0c46114e314c7701b
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  • [v2] ubsan: build ubsan.c more conservatively
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Commit Message

Arnd Bergmann July 22, 2019, 12:50 p.m. UTC
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.

Fixes: d08965a27e84 ("x86/uaccess, ubsan: Fix UBSAN vs. SMAP")
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/
Cc: stable@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v2:
- drop  -fno-conserve-stack
- fix the Fixes: line
---
 lib/Makefile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Andrey Ryabinin July 22, 2019, 12:56 p.m. UTC | #1
On 7/22/19 3:50 PM, Arnd Bergmann wrote:
> 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.
> 
> Fixes: d08965a27e84 ("x86/uaccess, ubsan: Fix UBSAN vs. SMAP")
> 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/
> Cc: stable@vger.kernel.org
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>


Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>

Patch
diff mbox series

diff --git a/lib/Makefile b/lib/Makefile
index 095601ce371d..29c02a924973 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -279,7 +279,8 @@  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)
+KASAN_SANITIZE_ubsan.o := n
+CFLAGS_ubsan.o := $(call cc-option, -fno-stack-protector) $(DISABLE_STACKLEAK_PLUGIN)
 
 obj-$(CONFIG_SBITMAP) += sbitmap.o