Fix null pointer dereference found by libfuzzer

1 files changed, 5 insertions, 4 deletions

diff --git a/signkey.c b/signkey.c
index bc63632..0900cf0 100644
--- a/signkey.c
+++ b/signkey.c
@@ -102,7 +102,8 @@ enum signkey_type signkey_type_from_name(const char* name, unsigned int namelen)
 	return DROPBEAR_SIGNKEY_NONE;
 }
 
-/* Returns a pointer to the key part specific to "type" */
+/* Returns a pointer to the key part specific to "type".
+Be sure to check both (ret != NULL) and (*ret != NULL) */
 void **
 signkey_key_ptr(sign_key *key, enum signkey_type type) {
 	switch (type) {
@@ -297,7 +298,7 @@ void buf_put_pub_key(buffer* buf, sign_key *key, enum signkey_type type) {
 #if DROPBEAR_ECDSA
 	if (signkey_is_ecdsa(type)) {
 		ecc_key **eck = (ecc_key**)signkey_key_ptr(key, type);
-		if (eck) {
+		if (eck && *eck) {
 			buf_put_ecdsa_pub_key(pubkeys, *eck);
 		}
 	}
@@ -334,7 +335,7 @@ void buf_put_priv_key(buffer* buf, sign_key *key, enum signkey_type type) {
 #if DROPBEAR_ECDSA
 	if (signkey_is_ecdsa(type)) {
 		ecc_key **eck = (ecc_key**)signkey_key_ptr(key, type);
-		if (eck) {
+		if (eck && *eck) {
 			buf_put_ecdsa_priv_key(buf, *eck);
 			TRACE(("leave buf_put_priv_key: ecdsa done"))
 			return;
@@ -498,7 +499,7 @@ void buf_put_sign(buffer* buf, sign_key *key, enum signkey_type type,
 #if DROPBEAR_ECDSA
 	if (signkey_is_ecdsa(type)) {
 		ecc_key **eck = (ecc_key**)signkey_key_ptr(key, type);
-		if (eck) {
+		if (eck && *eck) {
 			buf_put_ecdsa_sign(sigblob, *eck, data_buf);
 		}
 	}