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Date: Sun, 30 Jun 2019 22:44:28 -0500
From: Samuel Holland <samuel@...lland.org>
To: musl@...ts.openwall.com
Cc: Samuel Holland <samuel@...lland.org>
Subject: [PATCH] fix deadlock in synccall after threaded fork
synccall may be called by AS-safe functions such as setuid/setgid after
fork. although fork() resets libc.threads_minus_one, causing synccall to
take the single-threaded path, synccall still takes the thread list
lock. This lock may be held by another thread if for example fork()
races with pthread_create(). After fork(), the value of the lock is
meaningless, so clear it.
---
src/process/fork.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/src/process/fork.c b/src/process/fork.c
index 11286ef4..fb42478a 100644
--- a/src/process/fork.c
+++ b/src/process/fork.c
@@ -28,6 +28,7 @@ pid_t fork(void)
self->robust_list.off = 0;
self->robust_list.pending = 0;
self->next = self->prev = self;
+ __thread_list_lock = 0;
libc.threads_minus_1 = 0;
}
__restore_sigs(&set);
--
2.21.0
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