Author: tijl Date: Tue Oct 31 11:51:34 2017 New Revision: 325232 URL: https://svnweb.freebsd.org/changeset/base/325232
Log: Set the return address for stack entry points to zero. Stack unwinders treat zero as a stop condition. The value on the stack can be non-zero because thread stacks may be arbitrary memory provided via pthread_attr_setstack(3) or may be recycled from previous threads. Reference: https://lists.freebsd.org/pipermail/freebsd-current/2017-August/066855.html https://lists.freebsd.org/pipermail/freebsd-current/2017-October/067254.html Discussed with: kib MFC after: 1 week Modified: head/sys/amd64/amd64/vm_machdep.c head/sys/i386/i386/vm_machdep.c Modified: head/sys/amd64/amd64/vm_machdep.c ============================================================================== --- head/sys/amd64/amd64/vm_machdep.c Tue Oct 31 11:29:16 2017 (r325231) +++ head/sys/amd64/amd64/vm_machdep.c Tue Oct 31 11:51:34 2017 (r325232) @@ -508,6 +508,9 @@ cpu_set_upcall(struct thread *td, void (*entry)(void * (((uintptr_t)stack->ss_sp + stack->ss_size - 4) & ~0x0f) - 4; td->td_frame->tf_rip = (uintptr_t)entry; + /* Return address sentinel value to stop stack unwinding. */ + suword32((void *)td->td_frame->tf_rsp, 0); + /* Pass the argument to the entry point. */ suword32((void *)(td->td_frame->tf_rsp + sizeof(int32_t)), (uint32_t)(uintptr_t)arg); @@ -530,6 +533,9 @@ cpu_set_upcall(struct thread *td, void (*entry)(void * td->td_frame->tf_fs = _ufssel; td->td_frame->tf_gs = _ugssel; td->td_frame->tf_flags = TF_HASSEGS; + + /* Return address sentinel value to stop stack unwinding. */ + suword((void *)td->td_frame->tf_rsp, 0); /* Pass the argument to the entry point. */ td->td_frame->tf_rdi = (register_t)arg; Modified: head/sys/i386/i386/vm_machdep.c ============================================================================== --- head/sys/i386/i386/vm_machdep.c Tue Oct 31 11:29:16 2017 (r325231) +++ head/sys/i386/i386/vm_machdep.c Tue Oct 31 11:51:34 2017 (r325232) @@ -524,6 +524,9 @@ cpu_set_upcall(struct thread *td, void (*entry)(void * (((int)stack->ss_sp + stack->ss_size - 4) & ~0x0f) - 4; td->td_frame->tf_eip = (int)entry; + /* Return address sentinel value to stop stack unwinding. */ + suword((void *)td->td_frame->tf_esp, 0); + /* Pass the argument to the entry point. */ suword((void *)(td->td_frame->tf_esp + sizeof(void *)), (int)arg); _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
