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Fix abort_to_prompt bug if dynwind leave thunk expands the stack

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* libguile/vm.c (scm_i_vm_emergency_abort, abort_to_prompt): Unwinding
  the dynwind stack can run dynwind leave thunks, which may expand the
  stack, which may invalidate previously calculated SP / FP values.
  (Re)calculate SP/FP after unwinding, to avoid writing to unmapped
  memory.  Fixes compile errors seen on Ubuntu and some other ports.
This commit is contained in:
Andy Wingo 2020-01-02 13:27:23 +01:00
parent 76e436c892
commit e3e3e691f8
1 changed files with 8 additions and 5 deletions
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13
libguile/vm.c
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@ -1,4 +1,4 @@
/* Copyright 2001,2009-2015,2017-2019
/* Copyright 2001,2009-2015,2017-2020
Free Software Foundation, Inc.
This file is part of Guile.
@ -1360,9 +1360,6 @@ scm_i_vm_emergency_abort (SCM *tag_and_argv, size_t n)
abort ();
}
fp = vp->stack_top - fp_offset;
sp = vp->stack_top - sp_offset;
if (!(flags & SCM_F_DYNSTACK_PROMPT_ESCAPE_ONLY))
{
fprintf (stderr, "guile: fatal: emergency abort to non-linear prompt\n");
@ -1374,6 +1371,9 @@ scm_i_vm_emergency_abort (SCM *tag_and_argv, size_t n)
/* Unwind. */
scm_dynstack_unwind (dynstack, prompt);
fp = vp->stack_top - fp_offset;
sp = vp->stack_top - sp_offset;
/* Continuation gets nargs+1 values: the one more is for the cont. */
sp = sp - nargs - 1;
@ -1422,7 +1422,6 @@ abort_to_prompt (scm_thread *thread, uint8_t *saved_mra)
scm_misc_error ("abort", "Abort to unknown prompt", scm_list_1 (tag));
fp = vp->stack_top - fp_offset;
sp = vp->stack_top - sp_offset;
/* Only reify if the continuation referenced in the handler. */
if (flags & SCM_F_DYNSTACK_PROMPT_ESCAPE_ONLY)
@ -1439,6 +1438,10 @@ abort_to_prompt (scm_thread *thread, uint8_t *saved_mra)
/* Unwind. */
scm_dynstack_unwind (dynstack, prompt);
/* Recompute FP, as scm_dynstack_unwind may have expanded the stack. */
fp = vp->stack_top - fp_offset;
sp = vp->stack_top - sp_offset;
/* Continuation gets nargs+1 values: the one more is for the cont. */
sp = sp - nargs - 1;