mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-27 12:57:53 +00:00
x86/retpoline: Make sure there are no unconverted return thunks due to KCSAN
[ Upstream commit 2d7ce49f58
]
Enabling CONFIG_KCSAN leads to unconverted, default return thunks to
remain after patching.
As David Kaplan describes in his debugging of the issue, it is caused by
a couple of KCSAN-generated constructors which aren't processed by
objtool:
"When KCSAN is enabled, GCC generates lots of constructor functions
named _sub_I_00099_0 which call __tsan_init and then return. The
returns in these are generally annotated normally by objtool and fixed
up at runtime. But objtool runs on vmlinux.o and vmlinux.o does not
include a couple of object files that are in vmlinux, like
init/version-timestamp.o and .vmlinux.export.o, both of which contain
_sub_I_00099_0 functions. As a result, the returns in these functions
are not annotated, and the panic occurs when we call one of them in
do_ctors and it uses the default return thunk.
This difference can be seen by counting the number of these functions in the object files:
$ objdump -d vmlinux.o|grep -c "<_sub_I_00099_0>:"
2601
$ objdump -d vmlinux|grep -c "<_sub_I_00099_0>:"
2603
If these functions are only run during kernel boot, there is no
speculation concern."
Fix it by disabling KCSAN on version-timestamp.o and .vmlinux.export.o
so the extra functions don't get generated. KASAN and GCOV are already
disabled for those files.
[ bp: Massage commit message. ]
Closes: https://lore.kernel.org/lkml/20231016214810.GA3942238@dev-arch.thelio-3990X/
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Marco Elver <elver@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20231017165946.v4i2d4exyqwqq3bx@treble
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
parent
aa7f182795
commit
e2d8abf5af
2 changed files with 2 additions and 0 deletions
|
@ -60,4 +60,5 @@ include/generated/utsversion.h: FORCE
|
|||
$(obj)/version-timestamp.o: include/generated/utsversion.h
|
||||
CFLAGS_version-timestamp.o := -include include/generated/utsversion.h
|
||||
KASAN_SANITIZE_version-timestamp.o := n
|
||||
KCSAN_SANITIZE_version-timestamp.o := n
|
||||
GCOV_PROFILE_version-timestamp.o := n
|
||||
|
|
|
@ -19,6 +19,7 @@ quiet_cmd_cc_o_c = CC $@
|
|||
|
||||
ifdef CONFIG_MODULES
|
||||
KASAN_SANITIZE_.vmlinux.export.o := n
|
||||
KCSAN_SANITIZE_.vmlinux.export.o := n
|
||||
GCOV_PROFILE_.vmlinux.export.o := n
|
||||
targets += .vmlinux.export.o
|
||||
vmlinux: .vmlinux.export.o
|
||||
|
|
Loading…
Reference in a new issue