Hi Kees,
On Wed, Jul 23, 2025 at 10:50:24PM -0700, Kees Cook wrote:
> v4:
> - rebase on for-next/hardening tree (took subset of v3 patches)
> - improve commit logs for x86 and arm64 changes (Mike, Will, Ard)
> v3: https://lore.kernel.org/lkml/20250717231756.make.423-k...@kernel.org/
> v2: https://lore.kernel.org/lkml/20250523043251.it.550-k...@kernel.org/
> v1: https://lore.kernel.org/lkml/20250507180852.work.231-k...@kernel.org/
>
> Hi,
>
> These are the remaining changes needed to support Clang stack depth
> tracking for kstack_erase (nee stackleak).
A few build issues that I see when building next-20250725, which seem
related to this series.
1. I see
ld.lld: error: undefined symbol: __sanitizer_cov_stack_depth
>>> referenced by atags_to_fdt.c
>>> arch/arm/boot/compressed/atags_to_fdt.o:(atags_to_fdt)
make[5]: *** [arch/arm/boot/compressed/Makefile:152:
arch/arm/boot/compressed/vmlinux] Error 1
when building ARCH=arm allmodconfig on next-20250725. The following diff
appears to cure that one.
diff --git a/arch/arm/boot/compressed/Makefile
b/arch/arm/boot/compressed/Makefile
index f9075edfd773..f6142946b162 100644
--- a/arch/arm/boot/compressed/Makefile
+++ b/arch/arm/boot/compressed/Makefile
@@ -9,7 +9,6 @@ OBJS =
HEAD = head.o
OBJS += misc.o decompress.o
-CFLAGS_decompress.o += $(DISABLE_KSTACK_ERASE)
ifeq ($(CONFIG_DEBUG_UNCOMPRESS),y)
OBJS += debug.o
AFLAGS_head.o += -DDEBUG
@@ -96,7 +95,7 @@ KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
ccflags-y := -fpic $(call cc-option,-mno-single-pic-base,) -fno-builtin \
-I$(srctree)/scripts/dtc/libfdt -fno-stack-protector \
- -I$(obj)
+ -I$(obj) $(DISABLE_KSTACK_ERASE)
ccflags-remove-$(CONFIG_FUNCTION_TRACER) += -pg
asflags-y := -DZIMAGE
--
2. I see
kernel/kstack_erase.c:168:2: warning: function with attribute
'no_caller_saved_registers' should only call a function with attribute
'no_caller_saved_registers' or be compiled with '-mgeneral-regs-only'
[-Wexcessive-regsave]
168 | BUILD_BUG_ON(CONFIG_KSTACK_ERASE_TRACK_MIN_SIZE >
KSTACK_ERASE_SEARCH_DEPTH);
| ^
include/linux/build_bug.h:50:2: note: expanded from macro 'BUILD_BUG_ON'
50 | BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: "
#condition)
| ^
include/linux/build_bug.h:39:37: note: expanded from macro 'BUILD_BUG_ON_MSG'
39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
| ^
include/linux/compiler_types.h:568:2: note: expanded from macro
'compiletime_assert'
568 | _compiletime_assert(condition, msg, __compiletime_assert_,
__COUNTER__)
| ^
include/linux/compiler_types.h:556:2: note: expanded from macro
'_compiletime_assert'
556 | __compiletime_assert(condition, msg, prefix, suffix)
| ^
include/linux/compiler_types.h:549:4: note: expanded from macro
'__compiletime_assert'
549 | prefix ## suffix();
\
| ^
<scratch space>:97:1: note: expanded from here
97 | __compiletime_assert_521
| ^
kernel/kstack_erase.c:168:2: note: '__compiletime_assert_521' declared here
include/linux/build_bug.h:50:2: note: expanded from macro 'BUILD_BUG_ON'
50 | BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: "
#condition)
| ^
include/linux/build_bug.h:39:37: note: expanded from macro 'BUILD_BUG_ON_MSG'
39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
| ^
include/linux/compiler_types.h:568:2: note: expanded from macro
'compiletime_assert'
568 | _compiletime_assert(condition, msg, __compiletime_assert_,
__COUNTER__)
| ^
include/linux/compiler_types.h:556:2: note: expanded from macro
'_compiletime_assert'
556 | __compiletime_assert(condition, msg, prefix, suffix)
| ^
include/linux/compiler_types.h:546:26: note: expanded from macro
'__compiletime_assert'
546 | __noreturn extern void prefix ## suffix(void)
\
| ^
<scratch space>:96:1: note: expanded from here
96 | __compiletime_assert_521
| ^
kernel/kstack_erase.c:172:11: warning: function with attribute
'no_caller_saved_registers' should only call a function with attribute
'no_caller_saved_registers' or be compiled with '-mgeneral-regs-only'
[-Wexcessive-regsave]
172 | if (sp < current->lowest_stack &&
| ^
arch/x86/include/asm/current.h:28:17: note: expanded from macro 'current'
28 | #define current get_current()
| ^
arch/x86/include/asm/current.h:20:44: note: 'get_current' declared here
20 | static __always_inline struct task_struct *get_current(void)
| ^
kernel/kstack_erase.c:173:37: warning: function with attribute
'no_caller_saved_registers' should only call a function with attribute
'no_caller_saved_registers' or be compiled with '-mgeneral-regs-only'
[-Wexcessive-regsave]
173 | sp >= stackleak_task_low_bound(current)) {
| ^
arch/x86/include/asm/current.h:28:17: note: expanded from macro 'current'
28 | #define current get_current()
| ^
arch/x86/include/asm/current.h:20:44: note: 'get_current' declared here
20 | static __always_inline struct task_struct *get_current(void)
| ^
when building ARCH=i386 allmodconfig.
3. I see
In file included from kernel/fork.c:96:
include/linux/kstack_erase.h:29:37: error: passing 'const struct task_struct
*' to parameter of type 'struct task_struct *' discards qualifiers
[-Werror,-Wincompatible-pointer-types-discards-qualifiers]
29 | return (unsigned long)end_of_stack(tsk) + sizeof(unsigned
long);
| ^~~
include/linux/sched/task_stack.h:56:63: note: passing argument to parameter
'p' here
56 | static inline unsigned long *end_of_stack(struct task_struct *p)
| ^
when building ARCH=loongarch allmodconfig, which does not support
CONFIG_THREAD_INFO_IN_TASK it seems.
Cheers,
Nathan
