LyX 2.4 -- memory full when trying to copy a math block having boxed expression with 4 levels of nested deep subscript

[Alexander Dunlap]

On Sat, May 18, 2024, at 2:30 AM, Niranjana K M wrote:
> Dear LyX developers,
>     Thank you and congratulations for heading towards much awaited LyX-2.4.
> I have been using LyX-2.4-RC1 from last 6 months and yesterday accidentally i caught this strange behavior. And I even installed recently released LyX-2.4 and the behavior persisted in this version also. But i am not facing this problem in LyX-2.3.7.
>     The problem is, when I try to copy, by selecting and pressing Ctrl+C (or Copy from edit menu), a math block which is boxed and also having deep nested subscripts to at least 4 levels then my computer memory rapidly got consumed to the full (starting from 1GB to ~10GB) and in the end LyX closed with following message.
> 
> $ /usr/local/bin/lyx
> Error: Software exception Detected
> ----------------------------------------
> LyX has caught an exception, it will now attempt to save all unsaved documents and exit.
> Exception: std::bad_alloc
> Aborted
> 
> Following is the math block which caused it, (LyX code)
> \begin_inset Formula 
> \[
> \boxed{v=\left[v_{p}\right]_{a_{0}}}
> \]
> \end_inset
> 
> The file is also attached in the end and here is the screenshot of the math block.
> Screenshot from 2024-05-18 11-43-00.png
> 
> It is a legitimate construction and it gives no problem in LyX-2.3.7 (confirmed).
> If either the box is removed or the subscript 0 is removed from *a*, then it has no issues in copying.
> 
> All these versions I mentioned were compiled from source on Gentoo Linux. This LyX-2.4 was compiled with the following configuration,
> $ ./configure --without-included-boost
> Configuration
>   Host type:               x86_64-pc-linux-gnu
>   Special build flags:      build=release callback-printing use-hunspell use-aspell use-enchant
>   Bundled libraries:        nod
>   C++ Compiler:            g++ (13.2.1)
>   C++ Compiler flags:       -fPIC -O2 -std=c++17 
>   C++ Compiler user flags:   -std=c++17  -march=native -O2 -pipe
>   Linker flags:             -rdynamic
>   Linker user flags:       
>   Qt Frontend:
>       Qt version:   5.15.11
>   Packaging:               posix
>   LyX binary dir:          /usr/local/bin
>   LyX files dir:           /usr/local/share/lyx
> 
> I loved the new features in LyX-2.4 and don't want to go back to LyX-2.3.7 due to this issue. Please help in this regard.

I can reproduce this. I investigated a little and it seems that the problem is that the "while (true)" loop in the splitAndWrapInMText function in InsetMathBox.cpp is never terminating. I believe that the reason for this is that the logic in this function is not correctly identifying the matching XHTML end tag for a given start tag, since it doesn't take into account nested tags properly.


> 
> *Regards*
> *Niranjana*
> -- 
> lyx-devel mailing list
> lyx-devel at lists.lyx.org
> http://lists.lyx.org/mailman/listinfo/lyx-devel
> 
> 
> *Attachments:*
>  • test.24.lyx
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.lyx.org/pipermail/lyx-devel/attachments/20240518/637aef05/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Screenshot from 2024-05-18 11-43-00.png
Type: image/png
Size: 2400 bytes
Desc: not available
URL: <http://lists.lyx.org/pipermail/lyx-devel/attachments/20240518/637aef05/attachment.png>