[PATCH] mISDN: Fix null pointer dereference at mISDN_FsmNew

[Anton Vasilyev]

If mISDN_FsmNew() fails to allocate memory for jumpmatrix
then null pointer dereference will occur on any write to
jumpmatrix.

The patch adds check on successful allocation and
corresponding error handling.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Anton Vasilyev <vasilyev@xxxxxxxxx>
---
 drivers/isdn/mISDN/fsm.c    |  5 ++++-
 drivers/isdn/mISDN/fsm.h    |  2 +-
 drivers/isdn/mISDN/layer1.c |  3 +--
 drivers/isdn/mISDN/layer2.c | 15 +++++++++++++--
 drivers/isdn/mISDN/tei.c    | 20 +++++++++++++++++---
 5 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/drivers/isdn/mISDN/fsm.c b/drivers/isdn/mISDN/fsm.c
index 78fc5d5..92e6570 100644
--- a/drivers/isdn/mISDN/fsm.c
+++ b/drivers/isdn/mISDN/fsm.c
@@ -26,7 +26,7 @@
 
 #define FSM_TIMER_DEBUG 0
 
-void
+int
 mISDN_FsmNew(struct Fsm *fsm,
 	     struct FsmNode *fnlist, int fncount)
 {
@@ -34,6 +34,8 @@ mISDN_FsmNew(struct Fsm *fsm,
 
 	fsm->jumpmatrix = kzalloc(sizeof(FSMFNPTR) * fsm->state_count *
 				  fsm->event_count, GFP_KERNEL);
+	if (fsm->jumpmatrix == NULL)
+		return -ENOMEM;
 
 	for (i = 0; i < fncount; i++)
 		if ((fnlist[i].state >= fsm->state_count) ||
@@ -45,6 +47,7 @@ mISDN_FsmNew(struct Fsm *fsm,
 		} else
 			fsm->jumpmatrix[fsm->state_count * fnlist[i].event +
 					fnlist[i].state] = (FSMFNPTR) fnlist[i].routine;
+	return 0;
 }
 EXPORT_SYMBOL(mISDN_FsmNew);
 
diff --git a/drivers/isdn/mISDN/fsm.h b/drivers/isdn/mISDN/fsm.h
index 928f5be..e1def84 100644
--- a/drivers/isdn/mISDN/fsm.h
+++ b/drivers/isdn/mISDN/fsm.h
@@ -55,7 +55,7 @@ struct FsmTimer {
 	void *arg;
 };
 
-extern void mISDN_FsmNew(struct Fsm *, struct FsmNode *, int);
+extern int mISDN_FsmNew(struct Fsm *, struct FsmNode *, int);
 extern void mISDN_FsmFree(struct Fsm *);
 extern int mISDN_FsmEvent(struct FsmInst *, int , void *);
 extern void mISDN_FsmChangeState(struct FsmInst *, int);
diff --git a/drivers/isdn/mISDN/layer1.c b/drivers/isdn/mISDN/layer1.c
index bebc57b..3192b0e 100644
--- a/drivers/isdn/mISDN/layer1.c
+++ b/drivers/isdn/mISDN/layer1.c
@@ -414,8 +414,7 @@ l1_init(u_int *deb)
 	l1fsm_s.event_count = L1_EVENT_COUNT;
 	l1fsm_s.strEvent = strL1Event;
 	l1fsm_s.strState = strL1SState;
-	mISDN_FsmNew(&l1fsm_s, L1SFnList, ARRAY_SIZE(L1SFnList));
-	return 0;
+	return mISDN_FsmNew(&l1fsm_s, L1SFnList, ARRAY_SIZE(L1SFnList));
 }
 
 void
diff --git a/drivers/isdn/mISDN/layer2.c b/drivers/isdn/mISDN/layer2.c
index 7243a67..9ff0903 100644
--- a/drivers/isdn/mISDN/layer2.c
+++ b/drivers/isdn/mISDN/layer2.c
@@ -2247,15 +2247,26 @@ static struct Bprotocol X75SLP = {
 int
 Isdnl2_Init(u_int *deb)
 {
+	int res;
 	debug = deb;
 	mISDN_register_Bprotocol(&X75SLP);
 	l2fsm.state_count = L2_STATE_COUNT;
 	l2fsm.event_count = L2_EVENT_COUNT;
 	l2fsm.strEvent = strL2Event;
 	l2fsm.strState = strL2State;
-	mISDN_FsmNew(&l2fsm, L2FnList, ARRAY_SIZE(L2FnList));
-	TEIInit(deb);
+	res = mISDN_FsmNew(&l2fsm, L2FnList, ARRAY_SIZE(L2FnList));
+	if (res)
+		goto error;
+	res = TEIInit(deb);
+	if (res)
+		goto error_fsm;
 	return 0;
+
+error_fsm:
+	mISDN_FsmFree(&l2fsm);
+error:
+	mISDN_unregister_Bprotocol(&X75SLP);
+	return res;
 }
 
 void
diff --git a/drivers/isdn/mISDN/tei.c b/drivers/isdn/mISDN/tei.c
index 908127e..12d9e5f 100644
--- a/drivers/isdn/mISDN/tei.c
+++ b/drivers/isdn/mISDN/tei.c
@@ -1387,23 +1387,37 @@ create_teimanager(struct mISDNdevice *dev)
 
 int TEIInit(u_int *deb)
 {
+	int res;
 	debug = deb;
 	teifsmu.state_count = TEI_STATE_COUNT;
 	teifsmu.event_count = TEI_EVENT_COUNT;
 	teifsmu.strEvent = strTeiEvent;
 	teifsmu.strState = strTeiState;
-	mISDN_FsmNew(&teifsmu, TeiFnListUser, ARRAY_SIZE(TeiFnListUser));
+	res = mISDN_FsmNew(&teifsmu, TeiFnListUser, ARRAY_SIZE(TeiFnListUser));
+	if (res)
+		goto error;
 	teifsmn.state_count = TEI_STATE_COUNT;
 	teifsmn.event_count = TEI_EVENT_COUNT;
 	teifsmn.strEvent = strTeiEvent;
 	teifsmn.strState = strTeiState;
-	mISDN_FsmNew(&teifsmn, TeiFnListNet, ARRAY_SIZE(TeiFnListNet));
+	res = mISDN_FsmNew(&teifsmn, TeiFnListNet, ARRAY_SIZE(TeiFnListNet));
+	if (res)
+		goto error_smn;
 	deactfsm.state_count =  DEACT_STATE_COUNT;
 	deactfsm.event_count = DEACT_EVENT_COUNT;
 	deactfsm.strEvent = strDeactEvent;
 	deactfsm.strState = strDeactState;
-	mISDN_FsmNew(&deactfsm, DeactFnList, ARRAY_SIZE(DeactFnList));
+	res = mISDN_FsmNew(&deactfsm, DeactFnList, ARRAY_SIZE(DeactFnList));
+	if (res)
+		goto error_deact;
 	return 0;
+
+error_deact:
+	mISDN_FsmFree(&teifsmn);
+error_smn:
+	mISDN_FsmFree(&teifsmu);
+error:
+	return res;
 }
 
 void TEIFree(void)
-- 
2.7.4