On Tue, Jun 13, 2023 at 12:43:41AM +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 -E2BIG > is used to check for truncation instead of sizeof(dest). Perhaps say "PAGE_SIZE" here 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@xxxxxxxxx> > --- > drivers/usb/gadget/function/f_printer.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/usb/gadget/function/f_printer.c b/drivers/usb/gadget/function/f_printer.c > index 28db3e336e7d..10dc7c55c25f 100644 > --- a/drivers/usb/gadget/function/f_printer.c > +++ b/drivers/usb/gadget/function/f_printer.c > @@ -1211,8 +1211,8 @@ static ssize_t f_printer_opts_pnp_string_show(struct config_item *item, > if (!opts->pnp_string) > goto unlock; > > - result = strlcpy(page, opts->pnp_string, PAGE_SIZE); > - if (result >= PAGE_SIZE) { > + result = strscpy(page, opts->pnp_string, PAGE_SIZE); > + if (result == -E2BIG) { I think "< 1" might be a better test here. > result = PAGE_SIZE; > } else if (page[result - 1] != '\n' && result + 1 < PAGE_SIZE) { > page[result++] = '\n'; > -- > 2.41.0.162.gfafddb0af9-goog > > -Kees -- Kees Cook
