commit 685d450ab3823c578514ce6986d00c6e219abb43 Author: Nick Mathewson nickm@torproject.org Date: Sat Apr 19 13:07:30 2014 -0400

scan-build: avoid undef behaior in tor_inet_pton

If we had an address of the form "1.2.3.4" and we tried to pass it to tor_inet_pton with AF_INET6, it was possible for our 'eow' pointer to briefly move backwards to the point before the start of the string, before we moved it right back to the start of the string. C doesn't allow that, and though we haven't yet hit a compiler that decided to nuke us in response, it's best to fix.

So, be more explicit about requiring there to be a : before any IPv4 address part of the IPv6 address. We would have rejected addresses without a : for not being IPv6 later on anyway. --- src/common/compat.c | 4 +++- src/test/test_addr.c | 3 +++ 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/common/compat.c b/src/common/compat.c index c5945fb..8d816b9 100644 --- a/src/common/compat.c +++ b/src/common/compat.c @@ -2195,8 +2195,10 @@ tor_inet_pton(int af, const char *src, void *dst) else { unsigned byte1,byte2,byte3,byte4; char more; - for (eow = dot-1; eow >= src && TOR_ISDIGIT(*eow); --eow) + for (eow = dot-1; eow > src && TOR_ISDIGIT(*eow); --eow) ; + if (*eow != ':') + return 0; ++eow;

/* We use "scanf" because some platform inet_aton()s are too lax diff --git a/src/test/test_addr.c b/src/test/test_addr.c index cee2dcf..50011e6 100644 --- a/src/test/test_addr.c +++ b/src/test/test_addr.c @@ -346,6 +346,9 @@ test_addr_ip6_helpers(void) test_pton6_bad("a:::b:c"); test_pton6_bad(":::a:b:c"); test_pton6_bad("a:b:c:::"); + test_pton6_bad("1.2.3.4"); + test_pton6_bad(":1.2.3.4"); + test_pton6_bad(".2.3.4");

/* test internal checking */ test_external_ip("fbff:ffff::2:7", 0);