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| author | Nick Mathewson <nickm@torproject.org> | 2011-01-10 16:18:32 -0500 |
|---|---|---|
| committer | Nick Mathewson <nickm@torproject.org> | 2011-01-10 16:33:48 -0500 |
| commit | bd67b23fec5f9312769b9abf26787f074db05217 (patch) | |
| tree | dbd37a4f53f5e4aa03f13d7319c41cd9c200a4e9 | |
| parent | d43cba6c690d9c227b13cd7426285b82b9523611 (diff) | |
| download | tor-bd67b23fec5f9312769b9abf26787f074db05217.tar.gz tor-bd67b23fec5f9312769b9abf26787f074db05217.zip | |
Always nul-terminate the result passed to evdns_server_add_ptr_reply
In dnsserv_resolved(), we carefully made a nul-terminated copy of the
answer in a PTR RESOLVED cell... then never used that nul-terminated
copy. Ouch.
Surprisingly this one isn't as huge a security problem as it could be.
The only place where the input to dnsserv_resolved wasn't necessarily
nul-terminated was when it was called indirectly from relay.c with the
contents of a relay cell's payload. If the end of the payload was
filled with junk, eventdns.c would take the strdup() of the name [This
part is bad; we might crash there if the cell is in a bad part of the
stack or the heap] and get a name of at least length
495[*]. eventdns.c then rejects any name of length over 255, so the
bogus data would be neither transmitted nor altered.
[*] If the name was less than 495 bytes long, the client wouldn't
actually be reading off the end of the cell.
Nonetheless this is a reasonably annoying bug. Better fix it.
Found while looking at bug 2332, reported by doorss. Bugfix on
0.2.0.1-alpha.
| -rw-r--r-- | changes/bug2332 | 4 | ||||
| -rw-r--r-- | src/or/dnsserv.c | 2 |
2 files changed, 5 insertions, 1 deletions
diff --git a/changes/bug2332 b/changes/bug2332 new file mode 100644 index 0000000000..5f73ddd7af --- /dev/null +++ b/changes/bug2332 @@ -0,0 +1,4 @@ + o Minor bugfixes + - Fix a bug with handling misformed replies to reverse DNS lookup + requests in DNSPort. Bugfix on Tor 0.2.0.1-alpha. Related to a bug + reported by doorss. diff --git a/src/or/dnsserv.c b/src/or/dnsserv.c index 579080be3e..57c449311f 100644 --- a/src/or/dnsserv.c +++ b/src/or/dnsserv.c @@ -275,7 +275,7 @@ dnsserv_resolved(edge_connection_t *conn, char *ans = tor_strndup(answer, answer_len); evdns_server_request_add_ptr_reply(req, NULL, name, - (char*)answer, ttl); + ans, ttl); tor_free(ans); } else if (answer_type == RESOLVED_TYPE_ERROR) { err = DNS_ERR_NOTEXIST; |