[Asterisk-code-review] manager: fix digest auth for ami/http mechanism. (asterisk[master])

[Jaco Kroon]

Jaco Kroon has uploaded this change for review. ( https://gerrit.asterisk.org/8938


Change subject: manager: fix digest auth for ami/http mechanism.
......................................................................

manager: fix digest auth for ami/http mechanism.

Given that the a2 buffer ends up containing the user-supplied uri value
a static buffer can be trivially overflowed.  The potential DOS (memory
exhaustion) should be handled already in the http module by way of max
request size (specifically the MAX_HTTP_LINE_LENGTH).

ASTERISK-27841

Change-Id: I660609db13b8f9e5f9567f339dd804f4985d41b3
---
M main/manager.c
1 file changed, 14 insertions(+), 10 deletions(-)



  git pull ssh://gerrit.asterisk.org:29418/asterisk refs/changes/38/8938/1

diff --git a/main/manager.c b/main/manager.c
index 577c7f9..23e52b2 100644
--- a/main/manager.c
+++ b/main/manager.c
@@ -8006,22 +8006,26 @@
 
 	/* compute the expected response to compare with what we received */
 	{
-		char a2[256];
+		char *a2;
 		char a2_hash[256];
 		char resp[256];
 
 		/* XXX Now request method are hardcoded in A2 */
-		snprintf(a2, sizeof(a2), "%s:%s", ast_get_http_method(method), d.uri);
-		ast_md5_hash(a2_hash, a2);
+		a2 = ast_asprintf("%s:%s", ast_get_http_method(method), d.uri);
+		if (a2) {
+			ast_md5_hash(a2_hash, a2);
 
-		if (d.qop) {
-			/* RFC 2617 */
-			snprintf(resp, sizeof(resp), "%s:%08lx:%s:%s:auth:%s", user->a1_hash, nonce, d.nc, d.cnonce, a2_hash);
-		}  else {
-			/* RFC 2069 */
-			snprintf(resp, sizeof(resp), "%s:%08lx:%s", user->a1_hash, nonce, a2_hash);
+			if (d.qop) {
+				/* RFC 2617 */
+				snprintf(resp, sizeof(resp), "%s:%08lx:%s:%s:auth:%s", user->a1_hash, nonce, d.nc, d.cnonce, a2_hash);
+			}  else {
+				/* RFC 2069 */
+				snprintf(resp, sizeof(resp), "%s:%08lx:%s", user->a1_hash, nonce, a2_hash);
+			}
+			ast_md5_hash(resp_hash, resp);
+
+			ast_free(a2);
 		}
-		ast_md5_hash(resp_hash, resp);
 	}
 
 	if (strncasecmp(d.response, resp_hash, strlen(resp_hash))) {

-- 
To view, visit https://gerrit.asterisk.org/8938
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Gerrit-Project: asterisk
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: I660609db13b8f9e5f9567f339dd804f4985d41b3
Gerrit-Change-Number: 8938
Gerrit-PatchSet: 1
Gerrit-Owner: Jaco Kroon <jaco at uls.co.za>
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