For strnlen(), if the compiler detects that the maxlen argument exceeds
the valid memory size of the input string object, a compilation error may
occur.
For lastest linux-next source, changing ppc_kallsyms_lookup_name() to
__always_inline, using default ppc64_defconfig, and setting
CONFIG_EXPERT=y, CONFIG_PPC64_BIG_ENDIAN_ELF_ABI_V2=n,
CONFIG_CC_OPTIMIZE_FOR_SIZE=y. Then, when using gcc-15 for compilation,
the following error will be triggered:
```log
CC arch/powerpc/kernel/optprobes.o
In file included from ./arch/powerpc/include/asm/kprobes.h:24,
from ./include/linux/kprobes.h:31,
from arch/powerpc/kernel/optprobes.c:8:
In function ‘ppc_kallsyms_lookup_name’,
inlined from ‘arch_prepare_optimized_kprobe’ at
arch/powerpc/kernel/optprobes.c:209:21:
./arch/powerpc/include/asm/text-patching.h:232:13: error: ‘strnlen’ specified
bound 512 exceeds source size 19 [-Werror=stringop-overread]
232 | if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘ppc_kallsyms_lookup_name’,
inlined from ‘arch_prepare_optimized_kprobe’ at
arch/powerpc/kernel/optprobes.c:210:22:
./arch/powerpc/include/asm/text-patching.h:232:13: error: ‘strnlen’ specified
bound 512 exceeds source size 13 [-Werror=stringop-overread]
232 | if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
```
Refer to the implementation of fortify's strnlen(). If the string length
is a compile-time constant, do not call the strnlen() function.
Signed-off-by: Xie Yuanbin <[email protected]>
---
arch/powerpc/include/asm/text-patching.h | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/include/asm/text-patching.h
b/arch/powerpc/include/asm/text-patching.h
index e7f14720f630..ce1b2131980a 100644
--- a/arch/powerpc/include/asm/text-patching.h
+++ b/arch/powerpc/include/asm/text-patching.h
@@ -228,8 +228,13 @@ static inline unsigned long ppc_kallsyms_lookup_name(const
char *name)
/* check for dot variant */
char dot_name[1 + KSYM_NAME_LEN];
bool dot_appended = false;
+ size_t n_len = __compiletime_strlen(name);
+ const size_t n_size = __member_size(name);
- if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN)
+ if (n_len == SIZE_MAX || KSYM_NAME_LEN < n_size)
+ n_len = strnlen(name, KSYM_NAME_LEN);
+
+ if (n_len >= KSYM_NAME_LEN)
return 0;
if (name[0] != '.') {
--
2.51.0
