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authorLudovic Courtès <ludo@gnu.org>2018-06-29 22:28:48 +0200
committerLudovic Courtès <ludo@gnu.org>2018-06-29 22:28:48 +0200
commit23af45e248e8e2bec99c712842bf24d6661abbe2 (patch)
tree5938ca954470b8452458b3efe3ac067039c4ef31 /libguile/vm-engine.c
parentb87068eee7cfbe8dbc055b11221a931f5e9bec5c (diff)
downloadguile-23af45e248e8e2bec99c712842bf24d6661abbe2.tar.gz
vm: Fix stack-marking bug in multi-threaded programs.
Fixes <https://bugs.gnu.org/28211>. * libguile/vm-engine.c (call, call_label, handle_interrupts): Add 'new_fp' variable; set the dynamic link and return address of the frame at NEW_FP before setting 'vp->fp'. This fixes a bug whereby, in a multi-threaded context, the stack-marking code could run after vp->fp has been set but before its dynamic link has been set, leading the stack-walking code in 'scm_i_vm_mark_stack' to exit early on.
Diffstat (limited to 'libguile/vm-engine.c')
-rw-r--r--libguile/vm-engine.c27
1 files changed, 15 insertions, 12 deletions
diff --git a/libguile/vm-engine.c b/libguile/vm-engine.c
index 1aa4e9699..19ff3e498 100644
--- a/libguile/vm-engine.c
+++ b/libguile/vm-engine.c
@@ -548,7 +548,7 @@ VM_NAME (scm_i_thread *thread, struct scm_vm *vp,
VM_DEFINE_OP (1, call, "call", OP2 (X8_F24, X8_C24))
{
scm_t_uint32 proc, nlocals;
- union scm_vm_stack_element *old_fp;
+ union scm_vm_stack_element *old_fp, *new_fp;
UNPACK_24 (op, proc);
UNPACK_24 (ip[1], nlocals);
@@ -556,9 +556,10 @@ VM_NAME (scm_i_thread *thread, struct scm_vm *vp,
PUSH_CONTINUATION_HOOK ();
old_fp = vp->fp;
- vp->fp = SCM_FRAME_SLOT (old_fp, proc - 1);
- SCM_FRAME_SET_DYNAMIC_LINK (vp->fp, old_fp);
- SCM_FRAME_SET_RETURN_ADDRESS (vp->fp, ip + 2);
+ new_fp = SCM_FRAME_SLOT (old_fp, proc - 1);
+ SCM_FRAME_SET_DYNAMIC_LINK (new_fp, old_fp);
+ SCM_FRAME_SET_RETURN_ADDRESS (new_fp, ip + 2);
+ vp->fp = new_fp;
RESET_FRAME (nlocals);
@@ -586,7 +587,7 @@ VM_NAME (scm_i_thread *thread, struct scm_vm *vp,
{
scm_t_uint32 proc, nlocals;
scm_t_int32 label;
- union scm_vm_stack_element *old_fp;
+ union scm_vm_stack_element *old_fp, *new_fp;
UNPACK_24 (op, proc);
UNPACK_24 (ip[1], nlocals);
@@ -595,9 +596,10 @@ VM_NAME (scm_i_thread *thread, struct scm_vm *vp,
PUSH_CONTINUATION_HOOK ();
old_fp = vp->fp;
- vp->fp = SCM_FRAME_SLOT (old_fp, proc - 1);
- SCM_FRAME_SET_DYNAMIC_LINK (vp->fp, old_fp);
- SCM_FRAME_SET_RETURN_ADDRESS (vp->fp, ip + 3);
+ new_fp = SCM_FRAME_SLOT (old_fp, proc - 1);
+ SCM_FRAME_SET_DYNAMIC_LINK (new_fp, old_fp);
+ SCM_FRAME_SET_RETURN_ADDRESS (new_fp, ip + 3);
+ vp->fp = new_fp;
RESET_FRAME (nlocals);
@@ -3893,7 +3895,7 @@ VM_NAME (scm_i_thread *thread, struct scm_vm *vp,
NEXT (1);
{
- union scm_vm_stack_element *old_fp;
+ union scm_vm_stack_element *old_fp, *new_fp;
size_t old_frame_size = FRAME_LOCALS_COUNT ();
SCM proc = scm_i_async_pop (thread);
@@ -3907,9 +3909,10 @@ VM_NAME (scm_i_thread *thread, struct scm_vm *vp,
handle-interrupts opcode to handle any additional
interrupts. */
old_fp = vp->fp;
- vp->fp = SCM_FRAME_SLOT (old_fp, old_frame_size + 1);
- SCM_FRAME_SET_DYNAMIC_LINK (vp->fp, old_fp);
- SCM_FRAME_SET_RETURN_ADDRESS (vp->fp, ip);
+ new_fp = SCM_FRAME_SLOT (old_fp, old_frame_size + 1);
+ SCM_FRAME_SET_DYNAMIC_LINK (new_fp, old_fp);
+ SCM_FRAME_SET_RETURN_ADDRESS (new_fp, ip);
+ vp->fp = new_fp;
SP_SET (0, proc);