svn commit: r325232 - in head/sys: amd64/amd64 i386/i386
Tijl Coosemans
tijl at FreeBSD.org
Tue Oct 31 11:51:36 UTC 2017
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);
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