On Tue, Jun 13, 2023 at 3:30 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > 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)? > Ack. > > > > [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. > Curious, why "< 1" instead of "< 0"? > > 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
