On Mon, Oct 09, 2023 at 11:24:19PM +0200, Theo Buehler wrote: > On Mon, Oct 09, 2023 at 10:49:53PM +0200, Tobias Heider wrote: > > ipsecctl wrongly assumes that strings like the pf tag or > > the identities are always null terminated. > > The diff below fixes the cases that always kill my > > ipsecctl -m when running a fuzzer. > > > > ok? > > > > Index: pfkdump.c > > =================================================================== > > RCS file: /mount/openbsd/cvs/src/sbin/ipsecctl/pfkdump.c,v > > retrieving revision 1.57 > > diff -u -p -r1.57 pfkdump.c > > --- pfkdump.c 7 Aug 2023 04:10:08 -0000 1.57 > > +++ pfkdump.c 9 Oct 2023 20:41:54 -0000 > > @@ -406,9 +406,11 @@ print_tag(struct sadb_ext *ext, struct s > > { > > struct sadb_x_tag *stag = (struct sadb_x_tag *)ext; > > char *p; > > + int plen; > > > > p = (char *)(stag + 1); > > - printf("%s", p); > > + plen = (stag->sadb_x_tag_len * 8) - sizeof(*stag); > > If I understand correctly this attempts to undo the computation in > export_tag(). So this computes PADUP(stag->sadb_x_tag_taglen) where > PADUP() rounds up to the next multiple of 8. Should this not use > stag->sadb_x_tag_taglen - 1 instead, which is the strlen of the tag?
Thanks, I don't think this version can read out-of-bounds, see explanation below, but sadb_x_tag_taglen is certainly even better. > > > + printf("%.*s", plen, p); > > } > > > > static void > > @@ -590,10 +592,12 @@ static void > > print_ident(struct sadb_ext *ext, struct sadb_msg *msg, int opts) > > { > > struct sadb_ident *ident = (struct sadb_ident *)ext; > > + int ilen; > > > > - printf("type %s id %llu: %s", > > + ilen = (ident->sadb_ident_len * 8) - sizeof(*ident); > > Similar problem here, but there doesn't seem to be an easy way to get > the actual length of the identity. Doesn't this still overread? Not as far as I understand it. The whole payload is sadb_ident + string + eventual zero padding. We read the string until we hit the first null byte or the end of the whole payload which should be safe. > > > + printf("type %s id %llu: %.*s", > > lookup_name(identity_types, ident->sadb_ident_type), > > - ident->sadb_ident_id, (char *)(ident + 1)); > > + ident->sadb_ident_id, ilen, (char *)(ident + 1)); > > } > > > > static void > >