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patch 9.0.0577: buffer underflow with unexpected :finally

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Problem:    Buffer underflow with unexpected :finally.
Solution:   Check CSF_TRY can be found.
This commit is contained in:
Bram Moolenaar
2022-09-24 17:24:12 +01:00
parent b2209f213e
commit 96b9bf8f74
3 changed files with 291 additions and 270 deletions
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537
src/ex_eval.c
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@@ -1935,128 +1935,127 @@ ex_finally(exarg_T *eap)
if (cmdmod_error(FALSE))
return;
if (cstack->cs_trylevel <= 0 || cstack->cs_idx < 0)
eap->errmsg = _(e_finally_without_try);
else
for (idx = cstack->cs_idx; idx >= 0; --idx)
if (cstack->cs_flags[idx] & CSF_TRY)
break;
if (cstack->cs_trylevel <= 0 || idx < 0)
{
if (!(cstack->cs_flags[cstack->cs_idx] & CSF_TRY))
{
eap->errmsg = get_end_emsg(cstack);
for (idx = cstack->cs_idx - 1; idx > 0; --idx)
if (cstack->cs_flags[idx] & CSF_TRY)
break;
// Make this error pending, so that the commands in the following
// finally clause can be executed. This overrules also a pending
// ":continue", ":break", ":return", or ":finish".
pending = CSTP_ERROR;
}
else
idx = cstack->cs_idx;
eap->errmsg = _(e_finally_without_try);
return;
}
if (cstack->cs_flags[idx] & CSF_FINALLY)
if (!(cstack->cs_flags[cstack->cs_idx] & CSF_TRY))
{
eap->errmsg = get_end_emsg(cstack);
// Make this error pending, so that the commands in the following
// finally clause can be executed. This overrules also a pending
// ":continue", ":break", ":return", or ":finish".
pending = CSTP_ERROR;
}
if (cstack->cs_flags[idx] & CSF_FINALLY)
{
// Give up for a multiple ":finally" and ignore it.
eap->errmsg = _(e_multiple_finally);
return;
}
rewind_conditionals(cstack, idx, CSF_WHILE | CSF_FOR,
&cstack->cs_looplevel);
/*
* Don't do something when the corresponding try block never got active
* (because of an inactive surrounding conditional or after an error or
* interrupt or throw) or for a ":finally" without ":try" or a multiple
* ":finally". After every other error (did_emsg or the conditional
* errors detected above) or after an interrupt (got_int) or an
* exception (did_throw), the finally clause must be executed.
*/
skip = !(cstack->cs_flags[cstack->cs_idx] & CSF_TRUE);
if (!skip)
{
// When debugging or a breakpoint was encountered, display the
// debug prompt (if not already done). The user then knows that the
// finally clause is executed.
if (dbg_check_skipped(eap))
{
// Give up for a multiple ":finally" and ignore it.
eap->errmsg = _(e_multiple_finally);
return;
// Handle a ">quit" debug command as if an interrupt had
// occurred before the ":finally". That is, discard the
// original exception and replace it by an interrupt
// exception.
(void)do_intthrow(cstack);
}
rewind_conditionals(cstack, idx, CSF_WHILE | CSF_FOR,
&cstack->cs_looplevel);
/*
* Don't do something when the corresponding try block never got active
* (because of an inactive surrounding conditional or after an error or
* interrupt or throw) or for a ":finally" without ":try" or a multiple
* ":finally". After every other error (did_emsg or the conditional
* errors detected above) or after an interrupt (got_int) or an
* exception (did_throw), the finally clause must be executed.
* If there is a preceding catch clause and it caught the exception,
* finish the exception now. This happens also after errors except
* when this is a multiple ":finally" or one not within a ":try".
* After an error or interrupt, this also discards a pending
* ":continue", ":break", ":finish", or ":return" from the preceding
* try block or catch clause.
*/
skip = !(cstack->cs_flags[cstack->cs_idx] & CSF_TRUE);
cleanup_conditionals(cstack, CSF_TRY, FALSE);
if (!skip)
if (cstack->cs_idx >= 0
&& (cstack->cs_flags[cstack->cs_idx] & CSF_TRY))
{
// When debugging or a breakpoint was encountered, display the
// debug prompt (if not already done). The user then knows that the
// finally clause is executed.
if (dbg_check_skipped(eap))
{
// Handle a ">quit" debug command as if an interrupt had
// occurred before the ":finally". That is, discard the
// original exception and replace it by an interrupt
// exception.
(void)do_intthrow(cstack);
}
/*
* If there is a preceding catch clause and it caught the exception,
* finish the exception now. This happens also after errors except
* when this is a multiple ":finally" or one not within a ":try".
* After an error or interrupt, this also discards a pending
* ":continue", ":break", ":finish", or ":return" from the preceding
* try block or catch clause.
*/
cleanup_conditionals(cstack, CSF_TRY, FALSE);
if (cstack->cs_idx >= 0
&& (cstack->cs_flags[cstack->cs_idx] & CSF_TRY))
{
// Variables declared in the previous block can no longer be
// used.
leave_block(cstack);
enter_block(cstack);
}
/*
* Make did_emsg, got_int, did_throw pending. If set, they overrule
* a pending ":continue", ":break", ":return", or ":finish". Then
* we have particularly to discard a pending return value (as done
* by the call to cleanup_conditionals() above when did_emsg or
* got_int is set). The pending values are restored by the
* ":endtry", except if there is a new error, interrupt, exception,
* ":continue", ":break", ":return", or ":finish" in the following
* finally clause. A missing ":endwhile", ":endfor" or ":endif"
* detected here is treated as if did_emsg and did_throw had
* already been set, respectively in case that the error is not
* converted to an exception, did_throw had already been unset.
* We must not set did_emsg here since that would suppress the
* error message.
*/
if (pending == CSTP_ERROR || did_emsg || got_int || did_throw)
{
if (cstack->cs_pending[cstack->cs_idx] == CSTP_RETURN)
{
report_discard_pending(CSTP_RETURN,
cstack->cs_rettv[cstack->cs_idx]);
discard_pending_return(cstack->cs_rettv[cstack->cs_idx]);
}
if (pending == CSTP_ERROR && !did_emsg)
pending |= (THROW_ON_ERROR) ? CSTP_THROW : 0;
else
pending |= did_throw ? CSTP_THROW : 0;
pending |= did_emsg ? CSTP_ERROR : 0;
pending |= got_int ? CSTP_INTERRUPT : 0;
cstack->cs_pending[cstack->cs_idx] = pending;
// It's mandatory that the current exception is stored in the
// cstack so that it can be rethrown at the ":endtry" or be
// discarded if the finally clause is left by a ":continue",
// ":break", ":return", ":finish", error, interrupt, or another
// exception. When emsg() is called for a missing ":endif" or
// a missing ":endwhile"/":endfor" detected here, the
// exception will be discarded.
if (did_throw && cstack->cs_exception[cstack->cs_idx]
!= current_exception)
internal_error("ex_finally()");
}
/*
* Set CSL_HAD_FINA, so do_cmdline() will reset did_emsg,
* got_int, and did_throw and make the finally clause active.
* This will happen after emsg() has been called for a missing
* ":endif" or a missing ":endwhile"/":endfor" detected here, so
* that the following finally clause will be executed even then.
*/
cstack->cs_lflags |= CSL_HAD_FINA;
// Variables declared in the previous block can no longer be
// used.
leave_block(cstack);
enter_block(cstack);
}
/*
* Make did_emsg, got_int, did_throw pending. If set, they overrule
* a pending ":continue", ":break", ":return", or ":finish". Then
* we have particularly to discard a pending return value (as done
* by the call to cleanup_conditionals() above when did_emsg or
* got_int is set). The pending values are restored by the
* ":endtry", except if there is a new error, interrupt, exception,
* ":continue", ":break", ":return", or ":finish" in the following
* finally clause. A missing ":endwhile", ":endfor" or ":endif"
* detected here is treated as if did_emsg and did_throw had
* already been set, respectively in case that the error is not
* converted to an exception, did_throw had already been unset.
* We must not set did_emsg here since that would suppress the
* error message.
*/
if (pending == CSTP_ERROR || did_emsg || got_int || did_throw)
{
if (cstack->cs_pending[cstack->cs_idx] == CSTP_RETURN)
{
report_discard_pending(CSTP_RETURN,
cstack->cs_rettv[cstack->cs_idx]);
discard_pending_return(cstack->cs_rettv[cstack->cs_idx]);
}
if (pending == CSTP_ERROR && !did_emsg)
pending |= (THROW_ON_ERROR) ? CSTP_THROW : 0;
else
pending |= did_throw ? CSTP_THROW : 0;
pending |= did_emsg ? CSTP_ERROR : 0;
pending |= got_int ? CSTP_INTERRUPT : 0;
cstack->cs_pending[cstack->cs_idx] = pending;
// It's mandatory that the current exception is stored in the
// cstack so that it can be rethrown at the ":endtry" or be
// discarded if the finally clause is left by a ":continue",
// ":break", ":return", ":finish", error, interrupt, or another
// exception. When emsg() is called for a missing ":endif" or
// a missing ":endwhile"/":endfor" detected here, the
// exception will be discarded.
if (did_throw && cstack->cs_exception[cstack->cs_idx]
!= current_exception)
internal_error("ex_finally()");
}
/*
* Set CSL_HAD_FINA, so do_cmdline() will reset did_emsg,
* got_int, and did_throw and make the finally clause active.
* This will happen after emsg() has been called for a missing
* ":endif" or a missing ":endwhile"/":endfor" detected here, so
* that the following finally clause will be executed even then.
*/
cstack->cs_lflags |= CSL_HAD_FINA;
}
}
@@ -2076,185 +2075,183 @@ ex_endtry(exarg_T *eap)
if (cmdmod_error(FALSE))
return;
if (cstack->cs_trylevel <= 0 || cstack->cs_idx < 0)
eap->errmsg = _(e_endtry_without_try);
else
for (idx = cstack->cs_idx; idx >= 0; --idx)
if (cstack->cs_flags[idx] & CSF_TRY)
break;
if (cstack->cs_trylevel <= 0 || idx < 0)
{
/*
* Don't do something after an error, interrupt or throw in the try
* block, catch clause, or finally clause preceding this ":endtry" or
* when an error or interrupt occurred after a ":continue", ":break",
* ":return", or ":finish" in a try block or catch clause preceding this
* ":endtry" or when the try block never got active (because of an
* inactive surrounding conditional or after an error or interrupt or
* throw) or when there is a surrounding conditional and it has been
* made inactive by a ":continue", ":break", ":return", or ":finish" in
* the finally clause. The latter case need not be tested since then
* anything pending has already been discarded. */
skip = did_emsg || got_int || did_throw
eap->errmsg = _(e_endtry_without_try);
return;
}
/*
* Don't do something after an error, interrupt or throw in the try
* block, catch clause, or finally clause preceding this ":endtry" or
* when an error or interrupt occurred after a ":continue", ":break",
* ":return", or ":finish" in a try block or catch clause preceding this
* ":endtry" or when the try block never got active (because of an
* inactive surrounding conditional or after an error or interrupt or
* throw) or when there is a surrounding conditional and it has been
* made inactive by a ":continue", ":break", ":return", or ":finish" in
* the finally clause. The latter case need not be tested since then
* anything pending has already been discarded. */
skip = did_emsg || got_int || did_throw
|| !(cstack->cs_flags[cstack->cs_idx] & CSF_TRUE);
if (!(cstack->cs_flags[cstack->cs_idx] & CSF_TRY))
{
eap->errmsg = get_end_emsg(cstack);
if (!(cstack->cs_flags[cstack->cs_idx] & CSF_TRY))
{
eap->errmsg = get_end_emsg(cstack);
// Find the matching ":try" and report what's missing.
idx = cstack->cs_idx;
do
--idx;
while (idx > 0 && !(cstack->cs_flags[idx] & CSF_TRY));
rewind_conditionals(cstack, idx, CSF_WHILE | CSF_FOR,
&cstack->cs_looplevel);
skip = TRUE;
// Find the matching ":try" and report what's missing.
rewind_conditionals(cstack, idx, CSF_WHILE | CSF_FOR,
&cstack->cs_looplevel);
skip = TRUE;
/*
* If an exception is being thrown, discard it to prevent it from
* being rethrown at the end of this function. It would be
* discarded by the error message, anyway. Resets did_throw.
* This does not affect the script termination due to the error
* since "trylevel" is decremented after emsg() has been called.
*/
if (did_throw)
discard_current_exception();
/*
* If an exception is being thrown, discard it to prevent it from
* being rethrown at the end of this function. It would be
* discarded by the error message, anyway. Resets did_throw.
* This does not affect the script termination due to the error
* since "trylevel" is decremented after emsg() has been called.
*/
if (did_throw)
discard_current_exception();
// report eap->errmsg, also when there already was an error
did_emsg = FALSE;
}
else
{
idx = cstack->cs_idx;
// report eap->errmsg, also when there already was an error
did_emsg = FALSE;
}
else
{
idx = cstack->cs_idx;
// Check the flags only when not in a skipped block.
if (!skip && in_vim9script()
// Check the flags only when not in a skipped block.
if (!skip && in_vim9script()
&& (cstack->cs_flags[idx] & (CSF_CATCH|CSF_FINALLY)) == 0)
{
// try/endtry without any catch or finally: give an error and
// continue.
eap->errmsg = _(e_missing_catch_or_finally);
}
{
// try/endtry without any catch or finally: give an error and
// continue.
eap->errmsg = _(e_missing_catch_or_finally);
}
/*
* If we stopped with the exception currently being thrown at this
* try conditional since we didn't know that it doesn't have
* a finally clause, we need to rethrow it after closing the try
* conditional.
*/
if (did_throw && (cstack->cs_flags[idx] & CSF_TRUE)
&& !(cstack->cs_flags[idx] & CSF_FINALLY))
/*
* If we stopped with the exception currently being thrown at this
* try conditional since we didn't know that it doesn't have
* a finally clause, we need to rethrow it after closing the try
* conditional.
*/
if (did_throw && (cstack->cs_flags[idx] & CSF_TRUE)
&& !(cstack->cs_flags[idx] & CSF_FINALLY))
rethrow = TRUE;
}
// If there was no finally clause, show the user when debugging or
// a breakpoint was encountered that the end of the try conditional has
// been reached: display the debug prompt (if not already done). Do
// this on normal control flow or when an exception was thrown, but not
// on an interrupt or error not converted to an exception or when
// a ":break", ":continue", ":return", or ":finish" is pending. These
// actions are carried out immediately.
if ((rethrow || (!skip && !(cstack->cs_flags[idx] & CSF_FINALLY)
&& !cstack->cs_pending[idx]))
&& dbg_check_skipped(eap))
{
// Handle a ">quit" debug command as if an interrupt had occurred
// before the ":endtry". That is, throw an interrupt exception and
// set "skip" and "rethrow".
if (got_int)
{
skip = TRUE;
(void)do_intthrow(cstack);
// The do_intthrow() call may have reset did_throw or
// cstack->cs_pending[idx].
rethrow = FALSE;
if (did_throw && !(cstack->cs_flags[idx] & CSF_FINALLY))
rethrow = TRUE;
}
}
// If there was no finally clause, show the user when debugging or
// a breakpoint was encountered that the end of the try conditional has
// been reached: display the debug prompt (if not already done). Do
// this on normal control flow or when an exception was thrown, but not
// on an interrupt or error not converted to an exception or when
// a ":break", ":continue", ":return", or ":finish" is pending. These
// actions are carried out immediately.
if ((rethrow || (!skip
&& !(cstack->cs_flags[idx] & CSF_FINALLY)
&& !cstack->cs_pending[idx]))
&& dbg_check_skipped(eap))
{
// Handle a ">quit" debug command as if an interrupt had occurred
// before the ":endtry". That is, throw an interrupt exception and
// set "skip" and "rethrow".
if (got_int)
{
skip = TRUE;
(void)do_intthrow(cstack);
// The do_intthrow() call may have reset did_throw or
// cstack->cs_pending[idx].
rethrow = FALSE;
if (did_throw && !(cstack->cs_flags[idx] & CSF_FINALLY))
rethrow = TRUE;
}
}
/*
* If a ":return" is pending, we need to resume it after closing the
* try conditional; remember the return value. If there was a finally
* clause making an exception pending, we need to rethrow it. Make it
* the exception currently being thrown.
*/
if (!skip)
{
pending = cstack->cs_pending[idx];
cstack->cs_pending[idx] = CSTP_NONE;
if (pending == CSTP_RETURN)
rettv = cstack->cs_rettv[idx];
else if (pending & CSTP_THROW)
current_exception = cstack->cs_exception[idx];
}
/*
* If a ":return" is pending, we need to resume it after closing the
* try conditional; remember the return value. If there was a finally
* clause making an exception pending, we need to rethrow it. Make it
* the exception currently being thrown.
*/
if (!skip)
{
pending = cstack->cs_pending[idx];
cstack->cs_pending[idx] = CSTP_NONE;
if (pending == CSTP_RETURN)
rettv = cstack->cs_rettv[idx];
else if (pending & CSTP_THROW)
current_exception = cstack->cs_exception[idx];
}
/*
* Discard anything pending on an error, interrupt, or throw in the
* finally clause. If there was no ":finally", discard a pending
* ":continue", ":break", ":return", or ":finish" if an error or
* interrupt occurred afterwards, but before the ":endtry" was reached.
* If an exception was caught by the last of the catch clauses and there
* was no finally clause, finish the exception now. This happens also
* after errors except when this ":endtry" is not within a ":try".
* Restore "emsg_silent" if it has been reset by this try conditional.
*/
(void)cleanup_conditionals(cstack, CSF_TRY | CSF_SILENT, TRUE);
/*
* Discard anything pending on an error, interrupt, or throw in the
* finally clause. If there was no ":finally", discard a pending
* ":continue", ":break", ":return", or ":finish" if an error or
* interrupt occurred afterwards, but before the ":endtry" was reached.
* If an exception was caught by the last of the catch clauses and there
* was no finally clause, finish the exception now. This happens also
* after errors except when this ":endtry" is not within a ":try".
* Restore "emsg_silent" if it has been reset by this try conditional.
*/
(void)cleanup_conditionals(cstack, CSF_TRY | CSF_SILENT, TRUE);
if (cstack->cs_idx >= 0 && (cstack->cs_flags[cstack->cs_idx] & CSF_TRY))
leave_block(cstack);
--cstack->cs_trylevel;
if (cstack->cs_idx >= 0
&& (cstack->cs_flags[cstack->cs_idx] & CSF_TRY))
leave_block(cstack);
--cstack->cs_trylevel;
if (!skip)
{
report_resume_pending(pending,
if (!skip)
{
report_resume_pending(pending,
(pending == CSTP_RETURN) ? rettv :
(pending & CSTP_THROW) ? (void *)current_exception : NULL);
switch (pending)
{
case CSTP_NONE:
break;
switch (pending)
{
case CSTP_NONE:
break;
// Reactivate a pending ":continue", ":break", ":return",
// ":finish" from the try block or a catch clause of this try
// conditional. This is skipped, if there was an error in an
// (unskipped) conditional command or an interrupt afterwards
// or if the finally clause is present and executed a new error,
// interrupt, throw, ":continue", ":break", ":return", or
// ":finish".
case CSTP_CONTINUE:
ex_continue(eap);
break;
case CSTP_BREAK:
ex_break(eap);
break;
case CSTP_RETURN:
do_return(eap, FALSE, FALSE, rettv);
break;
case CSTP_FINISH:
do_finish(eap, FALSE);
break;
// Reactivate a pending ":continue", ":break", ":return",
// ":finish" from the try block or a catch clause of this try
// conditional. This is skipped, if there was an error in an
// (unskipped) conditional command or an interrupt afterwards
// or if the finally clause is present and executed a new error,
// interrupt, throw, ":continue", ":break", ":return", or
// ":finish".
case CSTP_CONTINUE:
ex_continue(eap);
break;
case CSTP_BREAK:
ex_break(eap);
break;
case CSTP_RETURN:
do_return(eap, FALSE, FALSE, rettv);
break;
case CSTP_FINISH:
do_finish(eap, FALSE);
break;
// When the finally clause was entered due to an error,
// interrupt or throw (as opposed to a ":continue", ":break",
// ":return", or ":finish"), restore the pending values of
// did_emsg, got_int, and did_throw. This is skipped, if there
// was a new error, interrupt, throw, ":continue", ":break",
// ":return", or ":finish". in the finally clause.
default:
if (pending & CSTP_ERROR)
did_emsg = TRUE;
if (pending & CSTP_INTERRUPT)
got_int = TRUE;
if (pending & CSTP_THROW)
rethrow = TRUE;
break;
}
// When the finally clause was entered due to an error,
// interrupt or throw (as opposed to a ":continue", ":break",
// ":return", or ":finish"), restore the pending values of
// did_emsg, got_int, and did_throw. This is skipped, if there
// was a new error, interrupt, throw, ":continue", ":break",
// ":return", or ":finish". in the finally clause.
default:
if (pending & CSTP_ERROR)
did_emsg = TRUE;
if (pending & CSTP_INTERRUPT)
got_int = TRUE;
if (pending & CSTP_THROW)
rethrow = TRUE;
break;
}
if (rethrow)
// Rethrow the current exception (within this cstack).
do_throw(cstack);
}
if (rethrow)
// Rethrow the current exception (within this cstack).
do_throw(cstack);
}
/*