curlopt does not check that file handles are valid - so if you send it a string for CURL_INFILE it will segfault.

patch below
Index: curl.c
===================================================================
RCS file: /repository/php4/ext/curl/curl.c,v
retrieving revision 1.97
diff -u -r1.97 curl.c
--- curl.c      13 Nov 2001 11:47:52 -0000      1.97
+++ curl.c      14 Nov 2001 02:16:47 -0000
@@ -706,8 +706,13 @@
        case CURLOPT_INFILE: 
        case CURLOPT_WRITEHEADER:
        case CURLOPT_STDERR: {
-               FILE *fp;
+               FILE *fp=NULL;
                ZEND_FETCH_RESOURCE(fp, FILE *, zvalue, -1, "File-Handle", php_file_le_fopen());
+                if (!fp) {
+                       php_error(E_WARNING,    "You must pass a file handle with the CURLOPT_FILE,"
+                                         "CURLOPT_INFILE, CURLOPT_WRITEHEADER and CURLOPT_STDERR arguments");
+                       RETURN_FALSE;
+               }
 
                error = CURLE_OK;
                switch (option) {