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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: linux-hams@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, Justin Stitt Content-Type: text/plain; charset="utf-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable 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 based on its usage with sprintf: | sprintf(hi.data.modename, "%sclk,%smodem,fclk=3D%d,bps=3D%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_pad() as it guarantees NUL-termination on the destination buffer while also NUL-padding (which is good+wanted behavior when copying data to userspace). Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncp= y-on-nul-terminated-strings [1] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Signed-off-by: Justin Stitt Reviewed-by: Kees Cook Reviewed-by: Simon Horman --- Changes in v2: - use strscpy_pad (thanks Kees) - bytes arrays are now considered "buffets" :) (thanks Kees) - Link to v1: https://lore.kernel.org/r/20231012-strncpy-drivers-net-hamrad= io-baycom_epp-c-v1-1-8f4097538ee4@google.com --- 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/bayco= m_epp.c index 83ff882f5d97..ccfc83857c26 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 *d= ev, struct ifreq *ifr, return 0; =20 case HDLCDRVCTL_DRIVERNAME: - strncpy(hi.data.drivername, "baycom_epp", sizeof(hi.data.drivername)); + strscpy_pad(hi.data.drivername, "baycom_epp", sizeof(hi.data.drivername)= ); break; =09 case HDLCDRVCTL_GETMODE: @@ -1091,7 +1091,7 @@ static int baycom_siocdevprivate(struct net_device *d= ev, struct ifreq *ifr, return baycom_setmode(bc, hi.data.modename); =20 case HDLCDRVCTL_MODELIST: - strncpy(hi.data.modename, "intclk,extclk,intmodem,extmodem,divider=3Dx", + strscpy_pad(hi.data.modename, "intclk,extclk,intmodem,extmodem,divider= =3Dx", sizeof(hi.data.modename)); break; =20 --- base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2 change-id: 20231012-strncpy-drivers-net-hamradio-baycom_epp-c-6e11c9483b9f Best regards, -- Justin Stitt