From d0d1ede191cbc8dfa1748990a052ef90f000b55b Mon Sep 17 00:00:00 2001
From: Matt Johnston <matt@ucc.asn.au>
Date: Fri, 5 Mar 2021 22:51:11 +0800
Subject: fuzz: fix crash in newtcpdirect(), don't close the channel too early

---
 fuzz.h             |  5 -----
 fuzz/fuzz-common.c | 20 --------------------
 netio.c            | 13 +++++++------
 3 files changed, 7 insertions(+), 31 deletions(-)

diff --git a/fuzz.h b/fuzz.h
index 4fc1ce0..95cb4d8 100644
--- a/fuzz.h
+++ b/fuzz.h
@@ -37,11 +37,6 @@ extern const char * const * fuzz_signkey_names;
 void fuzz_seed(const unsigned char* dat, unsigned int len);
 void fuzz_svr_hook_preloop(void);
 
-typedef void(*connect_callback)(int result, int sock, void* data, const char* errstring);
-struct dropbear_progress_connection *fuzz_connect_remote(const char* remotehost, const char* remoteport,
-    connect_callback cb, void* cb_data,
-    const char* bind_address, const char* bind_port);
-
 int fuzz_dropbear_listen(const char* address, const char* port,
         int *socks, unsigned int sockcount, char **errstring, int *maxfd);
 
diff --git a/fuzz/fuzz-common.c b/fuzz/fuzz-common.c
index 9cc6d75..c9a3391 100644
--- a/fuzz/fuzz-common.c
+++ b/fuzz/fuzz-common.c
@@ -235,26 +235,6 @@ int fuzz_spawn_command(int *ret_writefd, int *ret_readfd, int *ret_errfd, pid_t
 }
 
 
-struct dropbear_progress_connection *fuzz_connect_remote(const char* UNUSED(remotehost), const char* UNUSED(remoteport),
-    connect_callback cb, void* cb_data, 
-    const char* UNUSED(bind_address), const char* UNUSED(bind_port)) {
-    /* This replacement for connect_remote() has slightly different semantics
-    to the real thing. It should probably be replaced with something more sophisticated.
-    It calls the callback cb() immediately rather than
-    in a future session loop iteration with set_connect_fds()/handle_connect_fds().
-    This could cause problems depending on how connect_remote() is used. In particular
-    the callback can close a channel - that can cause use-after-free. */
-    char r;
-    genrandom((void*)&r, 1);
-    if (r & 1) {
-        int sock = wrapfd_new_dummy();
-        cb(DROPBEAR_SUCCESS, sock, cb_data, NULL);
-    } else {
-        cb(DROPBEAR_FAILURE, -1, cb_data, "errorstring");
-    }
-    return NULL;
-}
-
 /* Fake dropbear_listen, always returns failure for now.
 TODO make it sometimes return success with wrapfd_new_dummy() sockets.
 Making the listeners fake a new incoming connection will be harder. */
diff --git a/netio.c b/netio.c
index dbba5cd..0d69d3a 100644
--- a/netio.c
+++ b/netio.c
@@ -179,12 +179,6 @@ struct dropbear_progress_connection *connect_remote(const char* remotehost, cons
 	int err;
 	struct addrinfo hints;
 
-#if DROPBEAR_FUZZ
-	if (fuzz.fuzzing) {
-		return fuzz_connect_remote(remotehost, remoteport, cb, cb_data, bind_address, bind_port);
-	}
-#endif
-
 	c = m_malloc(sizeof(*c));
 	c->remotehost = m_strdup(remotehost);
 	c->remoteport = m_strdup(remoteport);
@@ -194,6 +188,13 @@ struct dropbear_progress_connection *connect_remote(const char* remotehost, cons
 
 	list_append(&ses.conn_pending, c);
 
+#if DROPBEAR_FUZZ
+	if (fuzz.fuzzing) {
+		c->errstring = m_strdup("fuzzing connect_remote always fails");
+		return c;
+	}
+#endif
+
 	memset(&hints, 0, sizeof(hints));
 	hints.ai_socktype = SOCK_STREAM;
 	hints.ai_family = AF_UNSPEC;
-- 
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