From 1b73f3761fc6bb166b9011b59b584f5273f9c0ed Mon Sep 17 00:00:00 2001 From: kib Date: Sat, 24 May 2014 10:23:06 +0000 Subject: Right now, the rtld prefork hook locks the rtld bind lock in the read mode. This allows the binder to be functional in the child after the fork (assuming no lazy loading of a filter is needed), but other rtld services which require write lock on rtld_bind_lock cause deadlock, if called by child. Change the _rtld_atfork() to lock the bind lock in write mode, making the rtld fully functional after the fork. Pre-resolve the symbols which are called by the libthr' fork() interposer, since dynamic resolution causes deadlock due to the rtld_bind_lock already owned in the write mode. Reported and tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 2 weeks --- libexec/rtld-elf/rtld_lock.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) (limited to 'libexec') diff --git a/libexec/rtld-elf/rtld_lock.c b/libexec/rtld-elf/rtld_lock.c index d1563e5..ea16c4d 100644 --- a/libexec/rtld-elf/rtld_lock.c +++ b/libexec/rtld-elf/rtld_lock.c @@ -365,8 +365,19 @@ _rtld_atfork_pre(int *locks) { RtldLockState ls[2]; + if (locks == NULL) + return; + + /* + * Warning: this does not work with the rtld compat locks + * above, since the thread signal mask is corrupted (set to + * all signals blocked) if two locks are taken in write mode. + * The caller of the _rtld_atfork_pre() must provide the + * working implementation of the locks, and libthr locks are + * fine. + */ wlock_acquire(rtld_phdr_lock, &ls[0]); - rlock_acquire(rtld_bind_lock, &ls[1]); + wlock_acquire(rtld_bind_lock, &ls[1]); /* XXXKIB: I am really sorry for this. */ locks[0] = ls[1].lockstate; @@ -378,6 +389,9 @@ _rtld_atfork_post(int *locks) { RtldLockState ls[2]; + if (locks == NULL) + return; + bzero(ls, sizeof(ls)); ls[0].lockstate = locks[2]; ls[1].lockstate = locks[0]; -- cgit v1.1