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.