Re: valgrind drd shows potential data race in curl_easy_init

From: Henrik Holst via curl-library <curl-library_at_lists.haxx.se>
Date: Thu, 20 Nov 2025 00:43:48 +0100

looks like you don't call curl_global_init() before starting your threads

/HH

Den tors 20 nov. 2025 kl 00:36 skrev Aman Grewal via curl-library <
curl-library_at_lists.haxx.se>:

> Hi all,
>
> I'm running my library under valgrind to try to find any bugs. I'm seeing
> this warning stemming from `curl_easy_init` when running drd.
>
> Command: `valgrind --tool=drd --read-var-info=yes --check-stack-var=yes
> --free-is-write=yes -s --gen-suppressions=all /test`
>
> Truncated Output:
> ==8== Thread 3:
> ==8== Conflicting load by thread 3 at 0x04949724 size 4
> ==8== at 0x48B8FA2: curl_easy_init (in
> /usr/lib/x86_64-linux-gnu/libcurl-gnutls.so.4.8.0)
> ==8== by 0x40014C1: thread_func (test.c:33)
> ==8== by 0x485B948: vgDrd_thread_wrapper (drd_pthread_intercepts.c:512)
> ==8== by 0x49E6AA3: start_thread (pthread_create.c:447)
> ==8== by 0x4A73A63: clone (clone.S:100)
> ==8== Allocation context: BSS section of
> /usr/lib/x86_64-linux-gnu/libcurl-gnutls.so.4.8.0
> ==8== Other segment start (thread 2)
> ==8== at 0x4A73A56: clone (clone.S:83)
> ==8== by 0x49E671F: ??? (allocatestack.c:605)
> ==8== by 0x67036BF: ???
> ==8== Other segment end (thread 2)
> ==8== at 0x4A759DB: connect (connect.c:26)
> ==8== by 0x48A7DEC: ??? (in
> /usr/lib/x86_64-linux-gnu/libcurl-gnutls.so.4.8.0)
> ==8== by 0x48B42E7: ??? (in
> /usr/lib/x86_64-linux-gnu/libcurl-gnutls.so.4.8.0)
> ==8== by 0x48B517F: ??? (in
> /usr/lib/x86_64-linux-gnu/libcurl-gnutls.so.4.8.0)
> ==8== by 0x48A8FC5: ??? (in
> /usr/lib/x86_64-linux-gnu/libcurl-gnutls.so.4.8.0)
> ==8== by 0x48EAED7: ??? (in
> /usr/lib/x86_64-linux-gnu/libcurl-gnutls.so.4.8.0)
> ==8== by 0x48ED5D9: curl_multi_perform (in
> /usr/lib/x86_64-linux-gnu/libcurl-gnutls.so.4.8.0)
> ==8== by 0x48BBE3A: curl_easy_perform (in
> /usr/lib/x86_64-linux-gnu/libcurl-gnutls.so.4.8.0)
> ==8== by 0x4001553: thread_func (test.c:38)
> ==8== by 0x485B948: vgDrd_thread_wrapper (drd_pthread_intercepts.c:512)
> ==8== by 0x49E6AA3: start_thread (pthread_create.c:447)
> ==8== by 0x4A73A63: clone (clone.S:100)
> ==8==
>
> When I run the same valgrind command on the sample code in
> https://curl.se/libcurl/c/threaded-ssl.html, I see similar warnings, so
> I'm hoping this is a spurious warning. Has anyone seen this before? Is it
> safe to add it to my suppressions file?
>
>
> I'm running this on Ubuntu 24.04 (LTS), and I'm using the libcurl3t64-gnutls
> package.
>
>
>
> Thanks,
> Aman Grewal
>
>
>
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Received on 2025-11-20