[PATCH] kallsyms: Replace all non-returning strlcpy with strscpy

[PATCH] kallsyms: Replace all non-returning strlcpy with strscpy

[Azeem Shaikh]

strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().
No return values were used, so direct replacement is safe.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89

Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
---
 kernel/kallsyms.c |    4 ++--
 kernel/params.c   |    2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 0f82c3d5a57d..7982cc9d497c 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -667,7 +667,7 @@ static int get_ksymbol_bpf(struct kallsym_iter *iter)
 {
 	int ret;
 
-	strlcpy(iter->module_name, "bpf", MODULE_NAME_LEN);
+	strscpy(iter->module_name, "bpf", MODULE_NAME_LEN);
 	iter->exported = 0;
 	ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
 			      &iter->value, &iter->type,
@@ -687,7 +687,7 @@ static int get_ksymbol_bpf(struct kallsym_iter *iter)
  */
 static int get_ksymbol_kprobe(struct kallsym_iter *iter)
 {
-	strlcpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN);
+	strscpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN);
 	iter->exported = 0;
 	return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end,
 				  &iter->value, &iter->type,
diff --git a/kernel/params.c b/kernel/params.c
index 6a7548979aa9..07d01f6ce9a2 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -847,7 +847,7 @@ static void __init param_sysfs_builtin(void)
 			name_len = 0;
 		} else {
 			name_len = dot - kp->name + 1;
-			strlcpy(modname, kp->name, name_len);
+			strscpy(modname, kp->name, name_len);
 		}
 		kernel_add_sysfs_param(modname, kp, name_len);
 	}
-- 
2.41.0.162.gfafddb0af9-goog

Re: [PATCH] kallsyms: Replace all non-returning strlcpy with strscpy

[Kees Cook]

On Wed, Jun 14, 2023 at 01:03:54AM +0000, Azeem Shaikh wrote:
> strlcpy() reads the entire source buffer first.
> This read may exceed the destination size limit.
> This is both inefficient and can lead to linear read
> overflows if a source string is not NUL-terminated [1].
> In an effort to remove strlcpy() completely [2], replace
> strlcpy() here with strscpy().
> No return values were used, so direct replacement is safe.
> 
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
> [2] https://github.com/KSPP/linux/issues/89
> 
> Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook

Re: [PATCH] kallsyms: Replace all non-returning strlcpy with strscpy

[Kees Cook]

On Wed, 14 Jun 2023 01:03:54 +0000, Azeem Shaikh wrote:
> strlcpy() reads the entire source buffer first.
> This read may exceed the destination size limit.
> This is both inefficient and can lead to linear read
> overflows if a source string is not NUL-terminated [1].
> In an effort to remove strlcpy() completely [2], replace
> strlcpy() here with strscpy().
> No return values were used, so direct replacement is safe.
> 
> [...]

Applied to for-next/hardening, thanks!

[1/1] kallsyms: Replace all non-returning strlcpy with strscpy
      https://git.kernel.org/kees/c/5a5d3a09dd76

-- 
Kees Cook