usb: gadget: function: printer: Replace strlcpy with strscpy

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 PAGE_SIZE.

[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>
Link: https://lore.kernel.org/r/20230615180318.400639-1-azeemshaikh38@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/gadget/function/f_printer.c b/drivers/usb/gadget/function/f_printer.c
index 28db3e336e7db877c3138a6742fb0c289b9127c2..b914256119692344b40a5d6458c9b52878eefd49 100644 (file)
--- 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 < 1) {
                result = PAGE_SIZE;
        } else if (page[result - 1] != '\n' && result + 1 < PAGE_SIZE) {
                page[result++] = '\n';