From 42e09be9c23e730d42b331384d128dbba8719c04 Mon Sep 17 00:00:00 2001 From: kib Date: Mon, 8 Feb 2016 19:24:13 +0000 Subject: If libthr.so is dlopened without RTLD_GLOBAL flag, the libthr symbols do not participate in the global symbols namespace, but rtld locks are still replaced and functions are interposed. In particular, __pthread_map_stacks_exec is resolved to the libc version. If a library is loaded later, which requires adjustment of the stack protection mode, rtld calls into libc __pthread_map_stacks_exec due to the symbols scope. The libc version might recurse into binder and recursively acquire rtld bind lock, causing the hang. Make libc __pthread_map_stacks_exec() interposed, which synchronizes rtld locks and version of the stack exec hook when libthr loaded, regardless of the symbol scope control or symbol resolution order. The __pthread_map_stacks_exec() symbol is removed from the private version in libthr since libc symbol now operates correctly in presence of libthr. Reported and tested by: markj Sponsored by: The FreeBSD Foundation MFC after: 2 weeks --- lib/libc/include/libc_private.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'lib/libc/include/libc_private.h') diff --git a/lib/libc/include/libc_private.h b/lib/libc/include/libc_private.h index 5caf9a3..554f3a2 100644 --- a/lib/libc/include/libc_private.h +++ b/lib/libc/include/libc_private.h @@ -224,6 +224,7 @@ enum { INTERPOS_kevent, INTERPOS_wait6, INTERPOS_ppoll, + INTERPOS_map_stacks_exec, INTERPOS_MAX }; @@ -381,6 +382,7 @@ int _elf_aux_info(int aux, void *buf, int buflen); struct dl_phdr_info; int __elf_phdr_match_addr(struct dl_phdr_info *, void *); void __init_elf_aux_vector(void); +void __libc_map_stacks_exec(); void _pthread_cancel_enter(int); void _pthread_cancel_leave(int); -- cgit v1.1