From 2e114248e086fb376405ed3f89b220f8586a2541 Mon Sep 17 00:00:00 2001 From: Justin Stitt Date: Tue, 2 Apr 2024 23:52:50 +0000 Subject: [PATCH] bpf: Replace deprecated strncpy with strscpy strncpy() is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces. bpf sym names get looked up and compared/cleaned with various string apis. This suggests they need to be NUL-terminated (strncpy() suggests this but does not guarantee it). | static int compare_symbol_name(const char *name, char *namebuf) | { | cleanup_symbol_name(namebuf); | return strcmp(name, namebuf); | } | static void cleanup_symbol_name(char *s) | { | ... | res = strstr(s, ".llvm."); | ... | } Use strscpy() as this method guarantees NUL-termination on the destination buffer. This patch also replaces two uses of strncpy() used in log.c. These are simple replacements as postfix has been zero-initialized on the stack and has source arguments with a size less than the destination's size. Note that this patch uses the new 2-argument version of strscpy introduced in commit e6584c3964f2f ("string: Allow 2-argument strscpy()"). Signed-off-by: Justin Stitt Signed-off-by: Daniel Borkmann Acked-by: Daniel Borkmann Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2] Link: https://github.com/KSPP/linux/issues/90 Link: https://lore.kernel.org/bpf/20240402-strncpy-kernel-bpf-core-c-v1-1-7cb07a426e78@google.com --- kernel/bpf/core.c | 4 ++-- kernel/bpf/log.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index ab400cdd7d7a..ae406a2814db 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -747,7 +747,7 @@ const char *__bpf_address_lookup(unsigned long addr, unsigned long *size, unsigned long symbol_start = ksym->start; unsigned long symbol_end = ksym->end; - strncpy(sym, ksym->name, KSYM_NAME_LEN); + strscpy(sym, ksym->name, KSYM_NAME_LEN); ret = sym; if (size) @@ -813,7 +813,7 @@ int bpf_get_kallsym(unsigned int symnum, unsigned long *value, char *type, if (it++ != symnum) continue; - strncpy(sym, ksym->name, KSYM_NAME_LEN); + strscpy(sym, ksym->name, KSYM_NAME_LEN); *value = ksym->start; *type = BPF_SYM_ELF_TYPE; diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c index 2a243cf37c60..4bd8f17a9f24 100644 --- a/kernel/bpf/log.c +++ b/kernel/bpf/log.c @@ -467,9 +467,9 @@ const char *reg_type_str(struct bpf_verifier_env *env, enum bpf_reg_type type) if (type & PTR_MAYBE_NULL) { if (base_type(type) == PTR_TO_BTF_ID) - strncpy(postfix, "or_null_", 16); + strscpy(postfix, "or_null_"); else - strncpy(postfix, "_or_null", 16); + strscpy(postfix, "_or_null"); } snprintf(prefix, sizeof(prefix), "%s%s%s%s%s%s%s",