strncpy() is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces.
We expect both hi.data.modename and hi.data.drivername to be NUL-terminated but not necessarily NUL-padded which is evident by its usage with sprintf: | sprintf(hi.data.modename, "%sclk,%smodem,fclk=%d,bps=%d%s", | bc->cfg.intclk ? "int" : "ext", | bc->cfg.extmodem ? "ext" : "int", bc->cfg.fclk, bc->cfg.bps, | bc->cfg.loopback ? ",loopback" : ""); Note that this data is copied out to userspace with: | if (copy_to_user(data, &hi, sizeof(hi))) ... however, the data was also copied FROM the user here: | if (copy_from_user(&hi, data, sizeof(hi))) Considering the above, a suitable replacement is `strscpy` [2] due to the fact that it guarantees NUL-termination on the destination buffer without unnecessarily NUL-padding. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2] Link: https://github.com/KSPP/linux/issues/90 Cc: [email protected] Signed-off-by: Justin Stitt <[email protected]> --- Note: build-tested only. Also, there are 33 instances of trailing whitespace in this file alone. I've opted to not remove them in this patch. --- drivers/net/hamradio/baycom_epp.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/hamradio/baycom_epp.c b/drivers/net/hamradio/baycom_epp.c index 83ff882f5d97..30a0fbb12b9c 100644 --- a/drivers/net/hamradio/baycom_epp.c +++ b/drivers/net/hamradio/baycom_epp.c @@ -1074,7 +1074,7 @@ static int baycom_siocdevprivate(struct net_device *dev, struct ifreq *ifr, return 0; case HDLCDRVCTL_DRIVERNAME: - strncpy(hi.data.drivername, "baycom_epp", sizeof(hi.data.drivername)); + strscpy(hi.data.drivername, "baycom_epp", sizeof(hi.data.drivername)); break; case HDLCDRVCTL_GETMODE: @@ -1091,7 +1091,7 @@ static int baycom_siocdevprivate(struct net_device *dev, struct ifreq *ifr, return baycom_setmode(bc, hi.data.modename); case HDLCDRVCTL_MODELIST: - strncpy(hi.data.modename, "intclk,extclk,intmodem,extmodem,divider=x", + strscpy(hi.data.modename, "intclk,extclk,intmodem,extmodem,divider=x", sizeof(hi.data.modename)); break; --- base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2 change-id: 20231012-strncpy-drivers-net-hamradio-baycom_epp-c-6e11c9483b9f Best regards, -- Justin Stitt <[email protected]>
