Date: Tue, 7 Nov 2017 17:07:45 +0000 (UTC) From: Tijl Coosemans <tijl@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: svn commit: r325518 - in stable/11/sys: amd64/amd64 i386/i386 Message-ID: <201711071707.vA7H7j8L079832@repo.freebsd.org>
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Author: tijl Date: Tue Nov 7 17:07:45 2017 New Revision: 325518 URL: https://svnweb.freebsd.org/changeset/base/325518 Log: MFC r325232 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 Modified: stable/11/sys/amd64/amd64/vm_machdep.c stable/11/sys/i386/i386/vm_machdep.c Directory Properties: stable/11/ (props changed) Modified: stable/11/sys/amd64/amd64/vm_machdep.c ============================================================================== --- stable/11/sys/amd64/amd64/vm_machdep.c Tue Nov 7 16:59:52 2017 (r325517) +++ stable/11/sys/amd64/amd64/vm_machdep.c Tue Nov 7 17:07:45 2017 (r325518) @@ -511,6 +511,9 @@ 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); @@ -533,6 +536,9 @@ 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: stable/11/sys/i386/i386/vm_machdep.c ============================================================================== --- stable/11/sys/i386/i386/vm_machdep.c Tue Nov 7 16:59:52 2017 (r325517) +++ stable/11/sys/i386/i386/vm_machdep.c Tue Nov 7 17:07:45 2017 (r325518) @@ -530,6 +530,9 @@ 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);
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