[PATCH v4] kobject: Replace strlcpy with strscpy

Azeem Shaikh
2023-08-31T14:01:19Z

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().

Direct replacement is safe here since return value of -errno
is used to check for truncation instead of sizeof(dest).

[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>
---
v4:
* Fixes errors reported by checkpatch.pl

v3:
* Fixed weird indentation.
* https://lore.kernel.org/all/20230830202021.4134348-1-azeemshaikh38@gmail.com/

v2:
* Updated error message to remove @len which is errno now.
* https://lore.kernel.org/all/20230830150136.3798414-1-azeemshaikh38@gmail.com/

v1:
* https://lore.kernel.org/all/20230703180528.3709258-1-azeemshaikh38@gmail.com/

lib/kobject_uevent.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c
index 7c44b7ae4c5c..fb9a2f06dd1e 100644
--- a/lib/kobject_uevent.c
+++ b/lib/kobject_uevent.c
@@ -254,10 +254,10 @@ static int init_uevent_argv(struct kobj_uevent_env *env, const char *subsystem)
int buffer_size = sizeof(env->buf) - env->buflen;
int len;

- len = strlcpy(&env->buf[env->buflen], subsystem, buffer_size);
- if (len >= buffer_size) {
- pr_warn("init_uevent_argv: buffer size of %d too small, needed %d\n",
- buffer_size, len);
+ len = strscpy(&env->buf[env->buflen], subsystem, buffer_size);
+ if (len < 0) {
+ pr_warn("%s: insufficient buffer space (%u left) for %s\n",
+ __func__, buffer_size, subsystem);
return -ENOMEM;
}

--
2.42.0.283.g2d96d420d3-goog