From curl-tracker-owner@cool.haxx.se Tue Feb 3 20:01:54 2009 Date: Tue, 03 Feb 2009 20:01:49 +0100 From: curl-tracker-owner@cool.haxx.se To: curl-tracker-owner@cool.haxx.se Subject: curl-tracker post from info@daniel-marschall.de requires approval As list administrator, your authorization is requested for the following mailing list posting: List: curl-tracker@cool.haxx.se From: info@daniel-marschall.de Subject: Re: cURL Bug? -- Segmentation Fault (fwd) Reason: Post to moderated list At your convenience, visit: http://cool.haxx.se/cgi-bin/mailman/admindb/curl-tracker to approve or deny the request. [ Part 2: "Included Message" ] Date: Tue, 3 Feb 2009 20:01:42 +0100 From: Daniel Marschall To: Daniel Stenberg , curl-library@cool.haxx.se, curl-tracker@cool.haxx.se Subject: Re: cURL Bug? -- Segmentation Fault (fwd) Hello. I only entered "apd-get install libcurl3-dev" in the system without knowing how to update a specific version or how to upgrade manually. The command "curl -v" does tell me: curl 7.15.5 (i486-pc-linux-gnu) libcurl/7.15.5 OpenSSL/0.9.8c zlib/1.2.3 libidn/0.6.5 Protocols: tftp ftp telnet dict ldap http file https ftps Features: GSS-Negotiate IDN IPv6 Largefile NTLM SSL libz I think, that is the newest that Debian supports as stable. The writer function WAS included in my original 500 lines code. So, the same error came with and without the buffer-writer-function. Since I had to abstract the program code to make a minimal crashing program, so I removed every line that did not make the crash disappearing, to show you the minimal program code required. And gdb did really output, that the curl_escape() function did make this memory-exception. I don't know the interna of the libCURL, I can only tell what the debugger tool wrote me. Every time the program crashes inside GDB, I get following debug line: Program received signal SIGSEGV, Segmentation fault. [Switching to Thread -1216652384 (LWP 23994)] 0xb7cf888a in curl_escape () from /usr/lib/libcurl.so.3 Here is my http function in the original case (before I did abstract to the minimal crash-demo-application - and it crashes with the same error): // Copied this function from haxx.se static int writer(char *data, size_t size, size_t nmemb, std::string *buffer) { // What we will return int result = 0; // Is there anything in the buffer? if (buffer != NULL) { // Append the data to the buffer buffer->append(data, size * nmemb); // How much did we write? result = size * nmemb; } return result; } static bool http_call (string url) { CURL *curl; logEvent(VERBOSE_LEVEL_DEBUG, "Calling URL: " + url); curl = curl_easy_init(); if(curl) { // URL übergeben curl_easy_setopt(curl, CURLOPT_URL, url.c_str()); // Keine Kopfzeile einblenden curl_easy_setopt(curl, CURLOPT_HEADER, false); // Verbindung danach beenden curl_easy_setopt(curl, CURLOPT_FORBID_REUSE, true); // Pufferoptionen char errorBuffer[CURL_ERROR_SIZE]; curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, errorBuffer); curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writer); string buffer; curl_easy_setopt(curl, CURLOPT_WRITEDATA, &buffer); // Benutzerdefinierter User-Agent-Name curl_easy_setopt(curl, CURLOPT_USERAGENT, "Hello World Browser"); // Einen Timeout setzen curl_easy_setopt(curl, CURLOPT_TIMEOUT, 1); // Weiterleitungen beachten, aber nur max. 50x curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, true); curl_easy_setopt(curl, CURLOPT_MAXREDIRS, 50); // Einen HTTP-Fehler-Statuscode beachten curl_easy_setopt(curl, CURLOPT_FAILONERROR, true); // SSL-Zertifikate nicht prüfen (Warnung! Sicherheitslücke) // http://ademar.name/blog/2006/04/curl-ssl-certificate-problem-v.html curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, false); curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, false); // Abfrage ausführen und Resultat speichern CURLcode res; res = curl_easy_perform(curl); // Clean up curl_easy_cleanup(curl); // Alles OK? if (res == CURLE_OK) { logEvent(VERBOSE_LEVEL_DEBUG, "URL successfully entered."); if (buffer != "\0") { logEvent(VERBOSE_LEVEL_DEBUG, "There was an output: " + buffer); } else { logEvent(VERBOSE_LEVEL_DEBUG, "There was no output."); } return true; } else { logEvent(VERBOSE_LEVEL_DEBUG, "Error while entering address: [" + IntToStr(res) + "] - " + errorBuffer); return false; } } else return false; } Best regards Daniel Marschall -------------------------------------------------- From: "Daniel Stenberg" Sent: Tuesday, February 03, 2009 7:45 PM To: "libcurl development" Cc: "Daniel Marschall" Subject: Re: cURL Bug? -- Segmentation Fault (fwd) > On Tue, 3 Feb 2009, Daniel Stenberg wrote: > >> I use G++ on a Linux Debian Etch with LibCURL3 > > 3 is the ABI number, it is better to tell us the version number. No matter > what, the most recent ABI 3 version is 2.5 years old so you'd be wise to > upgrade... > >> curl_easy_setopt(curl, CURLOPT_WRITEDATA, &buffer); > > With no write function set, this will clearly lead to crashes. The default > write function is fwrite() and fwrite() surely cannot deal with a pointer > to a 'string'... > >> With the GDB Tool I saw that the segmentation fault probably comes from >> curl_escape() everytime. > > I doubt that, as curl_escape() is never used by libcurl... it is only a > function its provides to the outside! > > -- > > / daniel.haxx.se > [ Part 3: "Included Message" ] Date: Tue, 03 Feb 2009 20:01:49 +0100 From: curl-tracker-request@cool.haxx.se Subject: confirm 0f17272b92a19839436abd3311888567ee1da333 If you reply to this message, keeping the Subject: header intact, Mailman will discard the held message. Do this if the message is spam. 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