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Fix a bug in handling special ABORT chunks.

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Thanks to Felix Weinrank for finding this issue using libfuzzer with
the userland stack.

MFC after:	3 days
This commit is contained in:
Michael Tuexen 2017-10-24 16:24:12 +00:00
parent e54fb4ff8c
commit 701492a5f6
1 changed files with 18 additions and 11 deletions
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29
sys/netinet/sctp_input.c
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@ -763,7 +763,8 @@ sctp_handle_nat_missing_state(struct sctp_tcb *stcb,
} }
static void /* Returns 1 if the stcb was aborted, 0 otherwise */
static int
sctp_handle_abort(struct sctp_abort_chunk *abort, sctp_handle_abort(struct sctp_abort_chunk *abort,
struct sctp_tcb *stcb, struct sctp_nets *net) struct sctp_tcb *stcb, struct sctp_nets *net)
{ {
@ -775,29 +776,29 @@ sctp_handle_abort(struct sctp_abort_chunk *abort,
SCTPDBG(SCTP_DEBUG_INPUT2, "sctp_handle_abort: handling ABORT\n"); SCTPDBG(SCTP_DEBUG_INPUT2, "sctp_handle_abort: handling ABORT\n");
if (stcb == NULL) if (stcb == NULL)
return; return (0);
len = ntohs(abort->ch.chunk_length); len = ntohs(abort->ch.chunk_length);
if (len > sizeof(struct sctp_chunkhdr)) { if (len >= sizeof(struct sctp_chunkhdr) + sizeof(struct sctp_error_cause)) {
/* /*
* Need to check the cause codes for our two magic nat * Need to check the cause codes for our two magic nat
* aborts which don't kill the assoc necessarily. * aborts which don't kill the assoc necessarily.
*/ */
struct sctp_gen_error_cause *cause; struct sctp_error_cause *cause;
cause = (struct sctp_gen_error_cause *)(abort + 1); cause = (struct sctp_error_cause *)(abort + 1);
error = ntohs(cause->code); error = ntohs(cause->code);
if (error == SCTP_CAUSE_NAT_COLLIDING_STATE) { if (error == SCTP_CAUSE_NAT_COLLIDING_STATE) {
SCTPDBG(SCTP_DEBUG_INPUT2, "Received Colliding state abort flags:%x\n", SCTPDBG(SCTP_DEBUG_INPUT2, "Received Colliding state abort flags:%x\n",
abort->ch.chunk_flags); abort->ch.chunk_flags);
if (sctp_handle_nat_colliding_state(stcb)) { if (sctp_handle_nat_colliding_state(stcb)) {
return; return (0);
} }
} else if (error == SCTP_CAUSE_NAT_MISSING_STATE) { } else if (error == SCTP_CAUSE_NAT_MISSING_STATE) {
SCTPDBG(SCTP_DEBUG_INPUT2, "Received missing state abort flags:%x\n", SCTPDBG(SCTP_DEBUG_INPUT2, "Received missing state abort flags:%x\n",
abort->ch.chunk_flags); abort->ch.chunk_flags);
if (sctp_handle_nat_missing_state(stcb, net)) { if (sctp_handle_nat_missing_state(stcb, net)) {
return; return (0);
} }
} }
} else { } else {
@ -832,6 +833,7 @@ sctp_handle_abort(struct sctp_abort_chunk *abort,
SCTP_SOCKET_UNLOCK(so, 1); SCTP_SOCKET_UNLOCK(so, 1);
#endif #endif
SCTPDBG(SCTP_DEBUG_INPUT2, "sctp_handle_abort: finished\n"); SCTPDBG(SCTP_DEBUG_INPUT2, "sctp_handle_abort: finished\n");
return (1);
} }
static void static void
@ -5121,11 +5123,16 @@ sctp_process_control(struct mbuf *m, int iphlen, int *offset, int length,
case SCTP_ABORT_ASSOCIATION: case SCTP_ABORT_ASSOCIATION:
SCTPDBG(SCTP_DEBUG_INPUT3, "SCTP_ABORT, stcb %p\n", SCTPDBG(SCTP_DEBUG_INPUT3, "SCTP_ABORT, stcb %p\n",
(void *)stcb); (void *)stcb);
if ((stcb) && netp && *netp)
sctp_handle_abort((struct sctp_abort_chunk *)ch,
stcb, *netp);
*offset = length; *offset = length;
return (NULL); if ((stcb != NULL) && (netp != NULL) && (*netp != NULL)) {
if (sctp_handle_abort((struct sctp_abort_chunk *)ch, stcb, *netp)) {
return (NULL);
} else {
return (stcb);
}
} else {
return (NULL);
}
break; break;
case SCTP_SHUTDOWN: case SCTP_SHUTDOWN:
SCTPDBG(SCTP_DEBUG_INPUT3, "SCTP_SHUTDOWN, stcb %p\n", SCTPDBG(SCTP_DEBUG_INPUT3, "SCTP_SHUTDOWN, stcb %p\n",