Messages in this thread Patch in this message | | | Date | Wed, 30 Aug 2023 15:34:52 -0700 | From | Kees Cook <> | Subject | Re: [PATCH v3] kobject: Replace strlcpy with strscpy |
| |
On Wed, Aug 30, 2023 at 08:20:21PM +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(). > > 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> > --- > v3: > * Fixed weird indentation. > > 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..032d81b959f0 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("init_uevent_argv: insufficient buffer space " > + "(%u left) for %s\n", buffer_size, subsystem); > return -ENOMEM; > }
I thought scripts/checkpatch.pl would warn about this, but kernel coding-style (as it is) says to not split strings. I'd expect this to be:
+ pr_warn("init_uevent_argv: insufficient buffer space (%u left) for %s\n", + buffer_size, subsystem);
-- Kees Cook
| |