Date: Tue, 14 Jan 2025 23:14:05 GMT From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 676be27133fa - main - libpthread_init(): ensure curthread == NULL until set explicitly Message-ID: <202501142314.50ENE57F072650@gitrepo.freebsd.org>
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The branch main has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=676be27133fa3296f3d9083732d8837a3eaa5ea4 commit 676be27133fa3296f3d9083732d8837a3eaa5ea4 Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2025-01-14 22:11:48 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2025-01-14 23:14:00 +0000 libpthread_init(): ensure curthread == NULL until set explicitly Otherwise libthr::_get_curthread() returns a garbage kept there from allocate_initial_tls(), until libthr initialization proceeds enough to set initial pcb->pcb_thread. The garbage pcb_thread was dereferenced as struct pthread and some memory read as TID. Since the read might not be consistent between reads, thr_malloc_umtx unlock sometimes returned EPERM instead of clearing the lock word. Reported by: markj Sponsored by: The FreeBSD Foundation MFC after: 1 week --- lib/libthr/thread/thr_init.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/lib/libthr/thread/thr_init.c b/lib/libthr/thread/thr_init.c index 708c425d69c1..8855491b91cb 100644 --- a/lib/libthr/thread/thr_init.c +++ b/lib/libthr/thread/thr_init.c @@ -334,6 +334,8 @@ _libpthread_init(struct pthread *curthread) /* Set the initial thread. */ if (curthread == NULL) { first = 1; + /* Force _get_curthread() return NULL until set. */ + _tcb_get()->tcb_thread = NULL; /* Create and initialize the initial thread. */ curthread = _thr_alloc(NULL); if (curthread == NULL)
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