irda: small read past the end of array in debug code

The "reason" can come from skb->data[] and it hasn't been capped so it can be from 0-255 instead of just 0-6. For example in irlmp_state_dtr() the code does: reason = skb->data[3]; ... irlmp_disconnect_indication(self, reason, skb); Also LMREASON has a couple other values which don't have entries in the irlmp_reasons[] array. And 0xff is a valid reason as well which means "unknown". So far as I can see we don't actually care about "reason" except for in the debug code. Signed-off-by: Dan Carpenter <[email protected]> Signed-off-by: David S. Miller <[email protected]>
kishon · Apr 19, 2013 · e15465e · e15465e
1 parent fd7fc25
commit e15465e
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Showing 3 changed files with 13 additions and 3 deletions.
diff --git a/include/net/irda/irlmp.h b/include/net/irda/irlmp.h
@@ -256,7 +256,8 @@ static inline __u32 irlmp_get_daddr(const struct lsap_cb *self)
 	return (self && self->lap) ? self->lap->daddr : 0;
 }
 
-extern const char *irlmp_reasons[];
+const char *irlmp_reason_str(LM_REASON reason);
+
 extern int sysctl_discovery_timeout;
 extern int sysctl_discovery_slots;
 extern int sysctl_discovery;

diff --git a/net/irda/iriap.c b/net/irda/iriap.c
@@ -303,7 +303,8 @@ static void iriap_disconnect_indication(void *instance, void *sap,
 {
 	struct iriap_cb *self;
 
-	IRDA_DEBUG(4, "%s(), reason=%s\n", __func__, irlmp_reasons[reason]);
+	IRDA_DEBUG(4, "%s(), reason=%s [%d]\n", __func__,
+		   irlmp_reason_str(reason), reason);
 
 	self = instance;
 

diff --git a/net/irda/irlmp.c b/net/irda/irlmp.c
@@ -66,8 +66,15 @@ const char *irlmp_reasons[] = {
 	"LM_LAP_RESET",
 	"LM_INIT_DISCONNECT",
 	"ERROR, NOT USED",
+	"UNKNOWN",
 };
 
+const char *irlmp_reason_str(LM_REASON reason)
+{
+	reason = min_t(size_t, reason, ARRAY_SIZE(irlmp_reasons) - 1);
+	return irlmp_reasons[reason];
+}
+
 /*
  * Function irlmp_init (void)
  *
@@ -747,7 +754,8 @@ void irlmp_disconnect_indication(struct lsap_cb *self, LM_REASON reason,
 {
 	struct lsap_cb *lsap;
 
-	IRDA_DEBUG(1, "%s(), reason=%s\n", __func__, irlmp_reasons[reason]);
+	IRDA_DEBUG(1, "%s(), reason=%s [%d]\n", __func__,
+		   irlmp_reason_str(reason), reason);
 	IRDA_ASSERT(self != NULL, return;);
 	IRDA_ASSERT(self->magic == LMP_LSAP_MAGIC, return;);