GNU bug report logs -
#61896
30.0.50; Emacs crashes because of an invalid free
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Reported by: Philip Kaludercic <philipk <at> posteo.net>
Date: Wed, 1 Mar 2023 20:26:02 UTC
Severity: normal
Found in version 30.0.50
Done: Stefan Kangas <stefankangas <at> gmail.com>
Bug is archived. No further changes may be made.
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Message #23 received at 61896 <at> debbugs.gnu.org (full text, mbox):
2 mars 2023 kl. 09.53 skrev Philip Kaludercic <philipk <at> posteo.net>:
>> Byte-code saw quite a bit of changes on master. Adding Mattias in
>> case he has some ideas.
>
> From what I recall, the address being freed was on the stack. How does
> the byte-code interpreter behave when the input is broken? Is there
> some way of validating if the byte-code is "coherent"? If I manually
> modify the byte code and replace random bytes, is the interpreter
> written to expect this kind of issue?
The very first thing is to make sure you don't have any lingering *.elc files generated during the period of incompatibility regarding `save-restriction`. That issue should have been resolved by now; let's not chase ghosts. The indication of a specpdl imbalance does point to this being a possible cause.
The byte-code interpreter normally assumes the code to be correct and performs few checks since every cycle counts here. There are some additional checks to be enabled: the general --enable-checking=all, and/or compiling with -DBYTE_CODE_SAFE=1 (or just adding
#define BYTE_CODE_SAFE 1
early in bytecode.c, which is what I tend to do).
These checks do not audit the specpdl balance directly but that would be something to add if you don't make further progress.
This bug report was last modified 1 year and 318 days ago.
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