mISDN: Fix null pointer dereference at mISDN_FsmNew

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@ispras.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 36 insertions, 9 deletions

diff --git a/drivers/isdn/mISDN/fsm.c b/drivers/isdn/mISDN/fsm.c
index 78fc5d5e905143..92e6570b11435e 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 928f5be192c1fd..e1def84902212e 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 bebc57b72138e7..3192b0eb394454 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 7243a6746f8b09..9ff0903a0e89fb 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 908127efccf8ce..12d9e5f4beb1f8 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)