On Wed, 24 Jan 2018 10:19:24 +0100 Phil Sutter <p...@nwl.cc> wrote: > Hi Stephen, > > On Tue, Jan 23, 2018 at 02:44:42PM -0800, Stephen Hemminger wrote: > > On Tue, 23 Jan 2018 17:40:47 +0100 > > Phil Sutter <p...@nwl.cc> wrote: > > > > > The following command segfaults if enp0s31f6 does not exist: > > > > > > | # ip -6 route add default proto ra metric 20100 \ > > > | nexthop via fe80:52:0:2040::1fc dev enp0s31f6 weight 1 \ > > > | nexthop via fe80:52:0:2040::1fe dev enp0s31f6 weight 1 > > > > > > Since the non-zero return code from parse_one_nh() is ignored, > > > parse_nexthops() continues iterating over the the same fields in argv > > > until buffer space is exhausted and eventually accesses unallocated > > > memory. > > > > > > Fix this by aborting on error in parse_nexthops() and make > > > iproute_modify() fail if parse_nexthops() did. > > > > > > Reported-by: Lennart Poettering <lpoet...@redhat.com> > > > Fixes: 2f406f2d0b4ef ("ip route: replace exits with returns") > > > Signed-off-by: Phil Sutter <p...@nwl.cc> > > > --- > > > ip/iproute.c | 7 ++++--- > > > 1 file changed, 4 insertions(+), 3 deletions(-) > > > > > > diff --git a/ip/iproute.c b/ip/iproute.c > > > index bf886fda9d761..d7accf57ac8d1 100644 > > > --- a/ip/iproute.c > > > +++ b/ip/iproute.c > > > @@ -871,7 +871,8 @@ static int parse_nexthops(struct nlmsghdr *n, struct > > > rtmsg *r, > > > memset(rtnh, 0, sizeof(*rtnh)); > > > rtnh->rtnh_len = sizeof(*rtnh); > > > rta->rta_len += rtnh->rtnh_len; > > > - parse_one_nh(n, r, rta, rtnh, &argc, &argv); > > > + if (parse_one_nh(n, r, rta, rtnh, &argc, &argv) < 0) > > > + return -1; > > > rtnh = RTNH_NEXT(rtnh); > > > } > > > > > > @@ -1318,8 +1319,8 @@ static int iproute_modify(int cmd, unsigned int > > > flags, int argc, char **argv) > > > addattr_l(&req.n, sizeof(req), RTA_METRICS, RTA_DATA(mxrta), > > > RTA_PAYLOAD(mxrta)); > > > } > > > > > > - if (nhs_ok) > > > - parse_nexthops(&req.n, &req.r, argc, argv); > > > + if (nhs_ok && parse_nexthops(&req.n, &req.r, argc, argv) < 0) > > > + return -1; > > > > > > if (req.r.rtm_family == AF_UNSPEC) > > > req.r.rtm_family = AF_INET; > > > > > > The real issue is that handling of invalid device is different than all the > > other > > possible semantic errors. > > > > My recommendations are: > > * change bad device to use invarg() which does exit > > * make functions that only return 0 void including > > parse_one_nh > > lwt_parse_encap > > get_addr > > > > Also, it looks like read_family converts any address family it doesn't know > > about to unspec > > that is stupid behavior as well. > > > > The original commit 2f406f2d0b4ef ("ip route: replace exits with returns") > > looks like well intentioned but suspect. Most of the errors in ip route > > indicate real issues where continuing is not a good plan. > > You're right, the use of invarg() for any other error effectively > prevents what said commit tried to achieve, so my fix is pretty > pointless in that regard. Yet I wonder why we still have 'ip -batch > -force' given that it's not useful. Maybe Élie is able to provide some > details about the use-case said commit tried to fix? > > Meanwhile I'll prepare some patches to address the shortcomings you > mentioned above.
The use case for batch (and force) is that there may be a large set of routes or qdisc operations where it is ok for some of them to fail because of responses from the kernel failing. I don't think batch should ever just continue if handed invalid syntax for device or address. There are some borderline cases, for example if a tunnel device could not be created and later steps depend on that name. Agree, lets get some real data on why the original patch was done.