sctp: fix use-after-free in pr_debug statement
Dmitry Vyukov reported a use-after-free in the code expanded by the
macro debug_post_sfx, which is caused by the use of the asoc pointer
after it was freed within sctp_side_effect() scope.
This patch fixes it by allowing sctp_side_effect to clear that asoc
pointer when the TCB is freed.
As Vlad explained, we also have to cover the SCTP_DISPOSITION_ABORT case
because it will trigger DELETE_TCB too on that same loop.
Also, there were places issuing SCTP_CMD_INIT_FAILED and ASSOC_FAILED
but returning SCTP_DISPOSITION_CONSUME, which would fool the scheme
above. Fix it by returning SCTP_DISPOSITION_ABORT instead.
The macro is already prepared to handle such NULL pointer.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
index 6098d4c..be23d5c 100644
--- a/net/sctp/sm_sideeffect.c
+++ b/net/sctp/sm_sideeffect.c
@@ -63,7 +63,7 @@
static int sctp_side_effects(sctp_event_t event_type, sctp_subtype_t subtype,
sctp_state_t state,
struct sctp_endpoint *ep,
- struct sctp_association *asoc,
+ struct sctp_association **asoc,
void *event_arg,
sctp_disposition_t status,
sctp_cmd_seq_t *commands,
@@ -1123,7 +1123,7 @@
debug_post_sfn();
error = sctp_side_effects(event_type, subtype, state,
- ep, asoc, event_arg, status,
+ ep, &asoc, event_arg, status,
&commands, gfp);
debug_post_sfx();
@@ -1136,7 +1136,7 @@
static int sctp_side_effects(sctp_event_t event_type, sctp_subtype_t subtype,
sctp_state_t state,
struct sctp_endpoint *ep,
- struct sctp_association *asoc,
+ struct sctp_association **asoc,
void *event_arg,
sctp_disposition_t status,
sctp_cmd_seq_t *commands,
@@ -1151,7 +1151,7 @@
* disposition SCTP_DISPOSITION_CONSUME.
*/
if (0 != (error = sctp_cmd_interpreter(event_type, subtype, state,
- ep, asoc,
+ ep, *asoc,
event_arg, status,
commands, gfp)))
goto bail;
@@ -1174,11 +1174,12 @@
break;
case SCTP_DISPOSITION_DELETE_TCB:
+ case SCTP_DISPOSITION_ABORT:
/* This should now be a command. */
+ *asoc = NULL;
break;
case SCTP_DISPOSITION_CONSUME:
- case SCTP_DISPOSITION_ABORT:
/*
* We should no longer have much work to do here as the
* real work has been done as explicit commands above.
diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
index 22c2bf3..f1f08c8 100644
--- a/net/sctp/sm_statefuns.c
+++ b/net/sctp/sm_statefuns.c
@@ -2976,7 +2976,7 @@
SCTP_INC_STATS(net, SCTP_MIB_IN_DATA_CHUNK_DISCARDS);
goto discard_force;
case SCTP_IERROR_NO_DATA:
- goto consume;
+ return SCTP_DISPOSITION_ABORT;
case SCTP_IERROR_PROTO_VIOLATION:
return sctp_sf_abort_violation(net, ep, asoc, chunk, commands,
(u8 *)chunk->subh.data_hdr, sizeof(sctp_datahdr_t));
@@ -3043,9 +3043,6 @@
sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, force);
return SCTP_DISPOSITION_DISCARD;
-consume:
- return SCTP_DISPOSITION_CONSUME;
-
}
/*
@@ -3093,7 +3090,7 @@
case SCTP_IERROR_BAD_STREAM:
break;
case SCTP_IERROR_NO_DATA:
- goto consume;
+ return SCTP_DISPOSITION_ABORT;
case SCTP_IERROR_PROTO_VIOLATION:
return sctp_sf_abort_violation(net, ep, asoc, chunk, commands,
(u8 *)chunk->subh.data_hdr, sizeof(sctp_datahdr_t));
@@ -3119,7 +3116,6 @@
SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
}
-consume:
return SCTP_DISPOSITION_CONSUME;
}
@@ -4825,9 +4821,6 @@
* if necessary to fill gaps.
*/
struct sctp_chunk *abort = arg;
- sctp_disposition_t retval;
-
- retval = SCTP_DISPOSITION_CONSUME;
if (abort)
sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort));
@@ -4845,7 +4838,7 @@
SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
- return retval;
+ return SCTP_DISPOSITION_ABORT;
}
/* We tried an illegal operation on an association which is closed. */
@@ -4960,12 +4953,10 @@
sctp_cmd_seq_t *commands)
{
struct sctp_chunk *abort = arg;
- sctp_disposition_t retval;
/* Stop T1-init timer */
sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
- retval = SCTP_DISPOSITION_CONSUME;
if (abort)
sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort));
@@ -4985,7 +4976,7 @@
sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
SCTP_PERR(SCTP_ERROR_USER_ABORT));
- return retval;
+ return SCTP_DISPOSITION_ABORT;
}
/*