Bug 475650

Summary: DRD does not work with C11 threads
Product: [Developer tools] valgrind Reporter: Dale Weiler <weilercdale>
Component: drdAssignee: Paul Floyd <pjfloyd>
Status: RESOLVED FIXED    
Severity: crash CC: bart.vanassche+kde, pjfloyd
Priority: NOR    
Version First Reported In: unspecified   
Target Milestone: ---   
Platform: Arch Linux   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description Dale Weiler 2023-10-15 08:26:33 UTC 
SUMMARY
DRD does not appear to support C11 threads.

STEPS TO REPRODUCE
Just create a thread in C with `thrd_create`

OBSERVED RESULT
==2451066== Process terminating with default action of signal 11 (SIGSEGV): dumping core
==2451066==  Access not within mapped region at address 0x7
==2451066==    at 0x4934634: pthread_attr_getdetachstate (pthread_attr_getdetachstate.c:29)
==2451066==    by 0x484ED7D: pthread_create_intercept (drd_pthread_intercepts.c:609)
==2451066==    by 0x484ED7D: pthread_create@* (drd_pthread_intercepts.c:640)
==2451066==    by 0x493F689: thrd_create@@GLIBC_2.34 (thrd_create.c:28)

EXPECTED RESULT
Should not crash

ADDITIONAL INFORMATION
I did some digging and it appears glibcs ntpl implements thrd_create by calling __pthread_create with an attr of ATTR_C11_THREAD which is just a macro for  ((void*)(uintptr_t)-1). Since this is not a null pointer, the check inside DRD's pthread_create_intercept succeeds then calls pthread_attr_getdetachstate with ((void*)(uintptr_t)-1) as the address of a valid attr struct.
Comment 1 Paul Floyd 2023-10-15 09:27:37 UTC 
For reference

https://en.cppreference.com/w/c/thread/thrd_create
Comment 2 Bart Van Assche 2023-10-15 15:41:05 UTC 
Does commit 6cea271f436d help?
Comment 3 Paul Floyd 2023-10-15 18:33:57 UTC 
The code fix looks OK, but I think that the configure test and regtest should use C11 rather than C++.
Comment 4 Paul Floyd 2023-10-15 19:05:06 UTC 
It's OK now on FreeBSD and I've also checked with musl and Illumos.
Comment 5 Bart Van Assche 2023-10-16 13:42:38 UTC 
The following two additional commits have been pushed:
* 45590cee742b ("drd/tests/thrd_create: Convert from C++ to C")
* a9d065c48d35 ("configure.ac: Convert the thrd_create() test from C++ to C")