From 8a15ac837819d19bb5f7d2cfa4ed9b4aa7690148 Mon Sep 17 00:00:00 2001 From: Konstantin Belousov Date: Thu, 18 Jun 2020 20:49:56 +0000 Subject: [PATCH] Fix execution of linux binary from multithreaded non-Linux process. If multithreaded non-Linux process execs Linux binary, then non-Linux threads different from the one that execing are cleared by single-threading at boundary, and then terminating them in post_execve(). Since at that time the process is already switched to linux ABI, linuxolator is involved in the thread clearing on boundary, but cannot find the emul data. Handle it by pre-creating emuldata for all threads in the execing process. Also remove a code in linux_proc_exec() handler that cleared emul data for other threads when execing from multithreaded Linux process. It is excessive. PR: 247020 Reported by: Martin FIlla Reported by: Henrique L. Amorim, Independent Security Researcher Reported by: Rodrigo Rubira Branco (BSDaemon), Amazon Web Services Reviewed by: markj Tested by: trasz Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D25293 --- sys/compat/linux/linux_emul.c | 40 +++++++++++++++++++++++------------ 1 file changed, 26 insertions(+), 14 deletions(-) diff --git a/sys/compat/linux/linux_emul.c b/sys/compat/linux/linux_emul.c index 7a92e0651c12..73678d963afd 100644 --- a/sys/compat/linux/linux_emul.c +++ b/sys/compat/linux/linux_emul.c @@ -291,22 +291,13 @@ linux_common_execve(struct thread *td, struct image_args *eargs) void linux_proc_exec(void *arg __unused, struct proc *p, struct image_params *imgp) { - struct thread *td = curthread; + struct thread *td; struct thread *othertd; #if defined(__amd64__) struct linux_pemuldata *pem; #endif - /* - * In a case of execing from Linux binary properly detach - * other threads from the user space. - */ - if (__predict_false(SV_PROC_ABI(p) == SV_ABI_LINUX)) { - FOREACH_THREAD_IN_PROC(p, othertd) { - if (td != othertd) - (p->p_sysent->sv_thread_detach)(othertd); - } - } + td = curthread; /* * In a case of execing to Linux binary we create Linux @@ -314,11 +305,32 @@ linux_proc_exec(void *arg __unused, struct proc *p, struct image_params *imgp) */ if (__predict_false((imgp->sysent->sv_flags & SV_ABI_MASK) == SV_ABI_LINUX)) { - - if (SV_PROC_ABI(p) == SV_ABI_LINUX) + if (SV_PROC_ABI(p) == SV_ABI_LINUX) { + /* + * Process already was under Linuxolator + * before exec. Update emuldata to reflect + * single-threaded cleaned state after exec. + */ linux_proc_init(td, NULL, 0); - else + } else { + /* + * We are switching the process to Linux emulator. + */ linux_proc_init(td, td, 0); + + /* + * Create a transient td_emuldata for all suspended + * threads, so that p->p_sysent->sv_thread_detach() == + * linux_thread_detach() can find expected but unused + * emuldata. + */ + FOREACH_THREAD_IN_PROC(td->td_proc, othertd) { + if (othertd != td) { + linux_proc_init(td, othertd, + LINUX_CLONE_THREAD); + } + } + } #if defined(__amd64__) /* * An IA32 executable which has executable stack will have the