From: Dan Carpenter Date: Wed, 6 Jul 2022 07:59:48 +0000 (+0300) Subject: can: slcan: use scnprintf() as a hardening measure X-Git-Tag: v6.6.17~6916^2~102^2~7 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=0159a9305d401fd21a1cda5e7baaf62122c46a5b;p=platform%2Fkernel%2Flinux-rpi.git can: slcan: use scnprintf() as a hardening measure The snprintf() function returns the number of bytes which *would* have been copied if there were no space. So, since this code does not check the return value, there if the buffer was not large enough then there would be a buffer overflow two lines later when it does: actual = sl->tty->ops->write(sl->tty, sl->xbuff, n); Use scnprintf() instead because that returns the number of bytes which were actually copied. Fixes: 52f9ac85b876 ("can: slcan: allow to send commands to the adapter") Signed-off-by: Dan Carpenter Link: https://lore.kernel.org/all/YsVA9KoY/ZSvNGYk@kili Signed-off-by: Marc Kleine-Budde --- diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c index 54d29a4..92bdd49 100644 --- a/drivers/net/can/slcan/slcan-core.c +++ b/drivers/net/can/slcan/slcan-core.c @@ -647,7 +647,7 @@ static int slcan_transmit_cmd(struct slcan *sl, const unsigned char *cmd) return -ENODEV; } - n = snprintf(sl->xbuff, sizeof(sl->xbuff), "%s", cmd); + n = scnprintf(sl->xbuff, sizeof(sl->xbuff), "%s", cmd); set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); actual = sl->tty->ops->write(sl->tty, sl->xbuff, n); sl->xleft = n - actual;