Date: Tue, 19 Sep 2017 20:09:58 +0000 (UTC) From: Michael Tuexen <tuexen@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r323774 - head/sys/netinet Message-ID: <201709192009.v8JK9wV2027639@repo.freebsd.org>
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Author: tuexen Date: Tue Sep 19 20:09:58 2017 New Revision: 323774 URL: https://svnweb.freebsd.org/changeset/base/323774 Log: Avoid an overflow when computing the staleness. This issue was found by running libfuzz on the userland stack. MFC after: 1 week Modified: head/sys/netinet/sctp_input.c Modified: head/sys/netinet/sctp_input.c ============================================================================== --- head/sys/netinet/sctp_input.c Tue Sep 19 18:18:24 2017 (r323773) +++ head/sys/netinet/sctp_input.c Tue Sep 19 20:09:58 2017 (r323774) @@ -2553,15 +2553,12 @@ sctp_handle_cookie_echo(struct mbuf *m, int iphlen, in /* Expire time is in Ticks, so we convert to seconds */ time_expires.tv_sec = cookie->time_entered.tv_sec + TICKS_TO_SEC(cookie->cookie_life); time_expires.tv_usec = cookie->time_entered.tv_usec; - /* - * TODO sctp_constants.h needs alternative time macros when _KERNEL - * is undefined. - */ if (timevalcmp(&now, &time_expires, >)) { /* cookie is stale! */ struct mbuf *op_err; struct sctp_error_stale_cookie *cause; - uint32_t tim; + struct timeval diff; + uint32_t staleness; op_err = sctp_get_mbuf_for_msg(sizeof(struct sctp_error_stale_cookie), 0, M_NOWAIT, 1, MT_DATA); @@ -2575,12 +2572,19 @@ sctp_handle_cookie_echo(struct mbuf *m, int iphlen, in cause->cause.code = htons(SCTP_CAUSE_STALE_COOKIE); cause->cause.length = htons((sizeof(struct sctp_paramhdr) + (sizeof(uint32_t)))); - /* seconds to usec */ - tim = (now.tv_sec - time_expires.tv_sec) * 1000000; - /* add in usec */ - if (tim == 0) - tim = now.tv_usec - cookie->time_entered.tv_usec; - cause->stale_time = htonl(tim); + diff = now; + timevalsub(&diff, &time_expires); + if (diff.tv_sec > UINT32_MAX / 1000000) { + staleness = UINT32_MAX; + } else { + staleness = diff.tv_sec * 1000000; + } + if (UINT32_MAX - staleness >= diff.tv_usec) { + staleness += diff.tv_usec; + } else { + staleness = UINT32_MAX; + } + cause->stale_time = htonl(staleness); sctp_send_operr_to(src, dst, sh, cookie->peers_vtag, op_err, mflowtype, mflowid, l_inp->fibnum, vrf_id, port);
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