[PATCH net] gtp: allow -1 to be specified as file description from userspace

Existing user space applications maintained by the Osmocom project are breaking since a recent fix that addresses incorrect error checking. Restore operation for user space programs that specify -1 as file descriptor to skip GTPv0 or GTPv1 only sockets. Fixes: defd8b3c37b0 ("gtp: fix a potential NULL pointer dereference") Reported-by: Pau Espin Pedrol <pespin(a)sysmocom.de> Signed-off-by: Pablo Neira Ayuso <pablo(a)netfilter.org> --- drivers/net/gtp.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c index a60bfb1abb7f..70f981887518 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -1702,20 +1702,24 @@ static int gtp_encap_enable(struct gtp_dev *gtp, struct nlattr *data[]) return -EINVAL; if (data[IFLA_GTP_FD0]) { - u32 fd0 = nla_get_u32(data[IFLA_GTP_FD0]); + int fd0 = nla_get_u32(data[IFLA_GTP_FD0]); - sk0 = gtp_encap_enable_socket(fd0, UDP_ENCAP_GTP0, gtp); - if (IS_ERR(sk0)) - return PTR_ERR(sk0); + if (fd0 >= 0) { + sk0 = gtp_encap_enable_socket(fd0, UDP_ENCAP_GTP0, gtp); + if (IS_ERR(sk0)) + return PTR_ERR(sk0); + } } if (data[IFLA_GTP_FD1]) { - u32 fd1 = nla_get_u32(data[IFLA_GTP_FD1]); + int fd1 = nla_get_u32(data[IFLA_GTP_FD1]); - sk1u = gtp_encap_enable_socket(fd1, UDP_ENCAP_GTP1U, gtp); - if (IS_ERR(sk1u)) { - gtp_encap_disable_sock(sk0); - return PTR_ERR(sk1u); + if (fd1 >= 0) { + sk1u = gtp_encap_enable_socket(fd1, UDP_ENCAP_GTP1U, gtp); + if (IS_ERR(sk1u)) { + gtp_encap_disable_sock(sk0); + return PTR_ERR(sk1u); + } } } -- 2.30.2