Bug 4937: cachemgr.cgi: unallocated memory access (#407)

... after base64_decode_update

Ensure that a terminator exists for the decoded string before
using str*() syscalls.

diff --git a/tools/cachemgr.cc b/tools/cachemgr.cc
index 98a6ae2316fefa98f29d15f07a94976cbacb5bc8..cdb953c0e797a7e26326bb97c86613f66e45b70c 100644 (file)
--- a/tools/cachemgr.cc
+++ b/tools/cachemgr.cc
@@ -1091,7 +1091,6 @@ make_pub_auth(cachemgr_request * req)
 static void
 decode_pub_auth(cachemgr_request * req)
 {
-    char *buf;
     const char *host_name;
     const char *time_str;
     const char *user_name;
@@ -1103,16 +1102,17 @@ decode_pub_auth(cachemgr_request * req)
     if (!req->pub_auth || strlen(req->pub_auth) < 4 + strlen(safe_str(req->hostname)))
         return;
 
-    size_t decodedLen = BASE64_DECODE_LENGTH(strlen(req->pub_auth));
-    buf = (char*)xmalloc(decodedLen);
+    char *buf = static_cast<char*>(xmalloc(BASE64_DECODE_LENGTH(strlen(req->pub_auth))+1));
     struct base64_decode_ctx ctx;
     base64_decode_init(&ctx);
+    size_t decodedLen = 0;
     if (!base64_decode_update(&ctx, &decodedLen, reinterpret_cast<uint8_t*>(buf), strlen(req->pub_auth), req->pub_auth) ||
             !base64_decode_final(&ctx)) {
         debug("cmgr: base64 decode failure. Incomplete auth token string.\n");
         xfree(buf);
         return;
     }
+    buf[decodedLen] = '\0';
 
     debug("cmgr: length ok\n");