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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