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| author | kib <kib@FreeBSD.org> | 2016-02-08 19:24:13 +0000 |
|---|---|---|
| committer | kib <kib@FreeBSD.org> | 2016-02-08 19:24:13 +0000 |
| commit | 42e09be9c23e730d42b331384d128dbba8719c04 (patch) | |
| tree | c91cbb77944f06638bce887f736eaeafed34a388 /lib/libthr/thread | |
| parent | 42bcd86bfbff24f6d52e96805b6d8d535c7db051 (diff) | |
| download | FreeBSD-src-42e09be9c23e730d42b331384d128dbba8719c04.zip FreeBSD-src-42e09be9c23e730d42b331384d128dbba8719c04.tar.gz | |
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
Diffstat (limited to 'lib/libthr/thread')
| -rw-r--r-- | lib/libthr/thread/thr_private.h | 2 | ||||
| -rw-r--r-- | lib/libthr/thread/thr_stack.c | 3 | ||||
| -rw-r--r-- | lib/libthr/thread/thr_syscalls.c | 1 |
3 files changed, 4 insertions, 2 deletions
diff --git a/lib/libthr/thread/thr_private.h b/lib/libthr/thread/thr_private.h index 0ba123d..6020e07 100644 --- a/lib/libthr/thread/thr_private.h +++ b/lib/libthr/thread/thr_private.h @@ -927,6 +927,8 @@ int __thr_sigwait(const sigset_t *set, int *sig); int __thr_sigwaitinfo(const sigset_t *set, siginfo_t *info); int __thr_swapcontext(ucontext_t *oucp, const ucontext_t *ucp); +void __thr_map_stacks_exec(void); + struct _spinlock; void __thr_spinunlock(struct _spinlock *lck); void __thr_spinlock(struct _spinlock *lck); diff --git a/lib/libthr/thread/thr_stack.c b/lib/libthr/thread/thr_stack.c index e5d149e..74e1329 100644 --- a/lib/libthr/thread/thr_stack.c +++ b/lib/libthr/thread/thr_stack.c @@ -161,9 +161,8 @@ singlethread_map_stacks_exec(void) rlim.rlim_cur, _rtld_get_stack_prot()); } -void __pthread_map_stacks_exec(void); void -__pthread_map_stacks_exec(void) +__thr_map_stacks_exec(void) { struct pthread *curthread, *thrd; struct stack *st; diff --git a/lib/libthr/thread/thr_syscalls.c b/lib/libthr/thread/thr_syscalls.c index 7c05697..712249b 100644 --- a/lib/libthr/thread/thr_syscalls.c +++ b/lib/libthr/thread/thr_syscalls.c @@ -652,6 +652,7 @@ __thr_interpose_libc(void) SLOT(kevent); SLOT(wait6); SLOT(ppoll); + SLOT(map_stacks_exec); #undef SLOT *(__libc_interposing_slot( INTERPOS__pthread_mutex_init_calloc_cb)) = |
