[PATCH 1/1] http: Fix crash when passing malformed URL

From: Anton Wuerfel <anton.wuerfel@fau.de>
Date: Mar 16, 2016, 10:54 UTC
Message-ID: <1458125647-32707-2-git-send-email-anton.wuerfel@fau.de>
In-Reply-To: <1458125647-32707-1-git-send-email-anton.wuerfel@fau.de>

When passing a malformed URL to http_init() in http.c, git dies from a null pointer dereference. An example for a malformed URL is http:/git-scm.com (note the single slash after the protocol). This patch adds simple error handling as git notices the malformed URL already, but never checks the error value.

When passing a malformed URL, credential_from_url(struct credential *c, const char *url) initializes *c with null values. When the existence of `://` in url is checked, the function returns without further change of *c. The null pointer dereference occurs in get_curl_handle () at http.c:593, when the `protocol` field of struct credential is strcmp'ed:

Program received signal SIGSEGV, Segmentation fault.
0x0000000000405efd in get_curl_handle () at http.c:593
593                     if (!strcmp(http_auth.protocol, "https")) {
---
 http.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/http.c b/http.c
index 69da445..80cf752 100644
--- a/http.c
+++ b/http.c
@@ -660,6 +660,9 @@ void http_init(struct remote *remote, const char *url, int proactive_auth)
 
 	http_is_verbose = 0;
 	normalized_url = url_normalize(url, &config.url);
+	
+	if (config.url.err)
+		die(_("libcurl: %s, URL: %s"), config.url.err, url);
 
 	git_config(urlmatch_config_entry, &config);
 	free(normalized_url);

-- 
2.8.0.rc1.108.g7827469