From 649621e3d54439ae232d726d7beef295d3887a68 Mon Sep 17 00:00:00 2001 From: Marcelo Ricardo Leitner Date: Fri, 8 Jan 2016 11:00:54 -0200 Subject: 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 Signed-off-by: Marcelo Ricardo Leitner Acked-by: Vlad Yasevich Signed-off-by: David S. Miller --- net/sctp/sm_sideeffect.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) (limited to 'net/sctp/sm_sideeffect.c') 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_cmd_interpreter(sctp_event_t event_type, 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 @@ int sctp_do_sm(struct net *net, sctp_event_t event_type, sctp_subtype_t subtype, 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 @@ int sctp_do_sm(struct net *net, sctp_event_t event_type, sctp_subtype_t subtype, 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 @@ static int sctp_side_effects(sctp_event_t event_type, sctp_subtype_t subtype, * 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 @@ static int sctp_side_effects(sctp_event_t event_type, sctp_subtype_t subtype, 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. -- cgit v1.1