On Tue, Jun 13, 2023 at 02:18:06PM +0000, Chuck Lever III wrote: > > > > On Jun 12, 2023, at 8:40 PM, Azeem Shaikh <azeemshaikh38@xxxxxxxxx> 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(). > > Using sprintf() seems cleaner to me: it would get rid of > the undocumented naked integer. Would that work for you? This is changing the "get" routine for reporting module parameters out of /sys. I think the right choice here is sysfs_emit(), as it performs the size tracking correctly. (Even the "default" sprintf() call should be replaced too, IMO.) > > > > Direct replacement is safe here since the getter in kernel_params_ops > > handles -errorno return [3]. > > s/errorno/errno/ > > > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy > > [2] https://github.com/KSPP/linux/issues/89 > > [3] https://elixir.bootlin.com/linux/v6.4-rc6/source/include/linux/moduleparam.h#L52 > > > > Signed-off-by: Azeem Shaikh <azeemshaikh38@xxxxxxxxx> > > --- > > net/sunrpc/svc.c | 8 ++++---- > > 1 file changed, 4 insertions(+), 4 deletions(-) > > > > diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c > > index e6d4cec61e47..e5f379c4fdb3 100644 > > --- a/net/sunrpc/svc.c > > +++ b/net/sunrpc/svc.c > > @@ -109,13 +109,13 @@ param_get_pool_mode(char *buf, const struct kernel_param *kp) > > switch (*ip) > > { > > case SVC_POOL_AUTO: > > - return strlcpy(buf, "auto\n", 20); > > + return strscpy(buf, "auto\n", 20); e.g. return sysfs_emit(buf, "auto\n"); ... > > case SVC_POOL_GLOBAL: > > - return strlcpy(buf, "global\n", 20); > > + return strscpy(buf, "global\n", 20); > > case SVC_POOL_PERCPU: > > - return strlcpy(buf, "percpu\n", 20); > > + return strscpy(buf, "percpu\n", 20); > > case SVC_POOL_PERNODE: > > - return strlcpy(buf, "pernode\n", 20); > > + return strscpy(buf, "pernode\n", 20); > > default: > > return sprintf(buf, "%d\n", *ip); and: return sysfs_emit(buf, "%d\n", *ip); -Kees -- Kees Cook
