On Wed, 14 Dec 2016, Theo van Klaveren wrote:
I am seeing an intermittent (2-3 times a week) segfault inside libcurl code,
and it is frequent enough that it is becoming a real problem. I'm having
problems finding the root cause so any help would be appreciated.
A bit of context: This is an application that is responsible for
fetching data from multiple sources via HTTP and uploading the results
to a central server via HTTPS.
No FTP or some other "ping-pong" protocol involved? It looks like the
Curl_close() that calls the function that crashes is done for the
"closure_handle".
It looks like something in Curl's state has become corrupted somewhere:
(gdb) list
3021 /* flush the timeout list too */
3022 while(list->size > 0)
<--- crash is here
3023 Curl_llist_remove(list, list->tail, NULL);
(gdb) print list
$9 = (struct curl_llist *) 0x0
This means (nowp->tv_sec || nowp->tv_usec) first evaluated true and yet
data->state.timeoutlist is NULL. That looks like a situation that shouldn't
happen.
The code that calls libcurl is pretty much a copy-paste of libcurl example
code, but I can post a (slightly redacted) version if it's needed.
Can you use that code against a public URL and experience a crash like this?
Any help in tracking down this segfault would be greatly appreciated!
In addition to Jay's suggestion, maybe just running the application with
valgrind could be a first test to see if it detects and wrongdoings.
--
/ daniel.haxx.se
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