Vscode: Regex Find can cause VS Code to Freeze

[Jason3S]

• VSCode Version: 1.14.1
• OS Version: Mac OSX Sierra 10.12.5 (16F73)

Steps to Reproduce:

1. code --disable-extensions
2. File->New File
3. Paste file from here: snippets.py (it happens with other files, but this is a simple example)
4. Edit->Find """(.*?\n?)+?""" regex
5. Try to remove the last ? from the regex.
6. The editor freezes at this point
7. Code Helper goes to 100% CPU.

Result:

Reproduces without extensions: Yes

[Jason3S]

It also happens with: 1.15.0-insider

[Jason3S]

I close it by accident. This is a real issue.

[rebornix]

Really good catch! Unfortunately search viewlet shares the same issue.

cc @roblourens

[rebornix]

The reason for the hang is the regex """(.*?\n?)+?""" has Catastrophic Backtracking, you can run into the same hang/100% CPU when executing this regex agains that snippet.py file in any browser.

We should have some timeout here to avoid the hang however.

[roblourens]

@rebornix it probably only impacts the search viewlet when the file is open, right? I think Rust's regex engine is not susceptible to this. So it would be fixed by any fix to the editor.

[rebornix]

@roblourens yes exactly as you said. It should just be a fix in the editor side.

[Spown]

Another case:

Steps:

1. Have a file with content

t({phrase: 'mail_text_q', locale: 'ru-RU'}, mailCtx)+'\n'+
t({phrase: 'mail_text_m', locale: 'ru-RU'}, mailCtx)+'\n'+

1. call search widget
2. set to RegEx
3. input (.*+'\n'+
4. try to add ) after the third character

(.*
   ^

[pascallaprade-beslogic]

I have another case of a regex search that hangs VS Code: /\*(.*\n?)*\*/.

• Pasting the regex immediately hangs VS Code, and a window appears after a few seconds, suggesting to reopen the window.
• Typing the regex manually will hang when typing the fourth * character specifically (I reproduced it many times to make sure it was this specific character hanging), so: /\*(.*\n?)*\ works, then as you type the * right after that, it hangs.

This is on VS Code 1.21.1, on Windows 10, both x64.

[ca1ek]

I found an another one that hangs. (.*)\(\d*\

• VSCode Version: 1.22.2
• OS Version: Windows 10 1709

I attempted to turn a rather large HTML file (577KB) into a CSV containing only data from that file. I can't share that file due to privacy reasons.

1. Press CTRL+H for search and replace
2. Enable regex and type in (.*)\(\d*\ and possibly punch in another space after it

There's about 25% CPU activity after it hangs, but I've been waiting a couple of minutes now. A regex shouldn't ever hang the whole editor.

Does this issue occur when all extensions are disabled?: Yes

[stefanJi]

Input order:

1. input \s19:.*
2. insert . to start
3. vscode freezed

[stefanJi]

Input order:

1. input \s19:.*
2. insert . to start
3. vscode freezed

Vscod Version: 1.31.1
Os: mac 10.14.3

[jtakalai]

Curious that it's such a problem since other editors like Sublime don't have a problem with highlighting regex matches... Why is newline such an issue? Shouldn't it be just another character?

[hobpet]

Curious that it's such a problem since other editors like Sublime don't have a problem with highlighting regex matches... Why is newline such an issue? Shouldn't it be just another character?

Actually I've tested my search in Sublime and there I have the following messages (but no crash!):

ERROR: Regex exhausted stack searching file
ERROR: Regex complexity too high searching file

[emilygdavis]

I am running into this, too, for Find in a single file (not the global find/replace). I'm encountering the issue simply by using a pipe character (|) in my RegEx, when I have not yet populated characters after the pipe character. If I try enter something like

element|

(eventually intending to type element|getElement), VSCode freezes up, before I've even hit "Enter" to do the Find.

This is on VSCode version 1.39.2, on Max OSX Mojave (v10.14.6).

[Fadavvi]

Version: 1.41.1 (user setup)
Commit: 26076a4de974ead31f97692a0d32f90d735645c0
Date: 2019-12-18T14:58:56.166Z
Electron: 6.1.5
Chrome: 76.0.3809.146
Node.js: 12.4.0
V8: 7.6.303.31-electron.0
OS: Windows_NT x64 10.0.18363

and still

[roblourens]

@Fadavvi please open a new issue, I can't repro it. I'm curious whether it happens without the "whole word" toggle enabled, or in a shorter file.

[Fadavvi]

@Fadavvi please open a new issue, I can't repro it. I'm curious whether it happens without the "whole word" toggle enabled, or in a shorter file.

OK. I'll open a new issue. It happen only on some special files. I can't find similarity of files!

[jmlowenthal]

I am running into this, too, for Find in a single file (not the global find/replace). I'm encountering the issue simply by using a pipe character (|) in my RegEx, when I have not yet populated characters after the pipe character. If I try enter something like

element|

(eventually intending to type element|getElement), VSCode freezes up, before I've even hit "Enter" to do the Find.

This is on VSCode version 1.39.2, on Max OSX Mojave (v10.14.6).

+1 to this on VSCode 1.45.0 on Linux x64 5.6.0-1-amd64 (Debian)

[Artemis21]

Very simple regex to reproduce: (x|)

[jmlowenthal]

Looks to be fixed in 1.45.1 for me. @Artemis21 can you repro in 1.45.1?

[ndbroadbent]

I'm using VS Code 1.45.1, and I've just found another regex that will cause VS Code to freeze: "([^]+\n)+"

I've reproduced this with some minimal examples: https://gist.github.com/ndbroadbent/bb5e246b05488296576ee3dc39d40e38

(I've tested these with code --disable-extensions to disable all extensions.)

One example freezes my computer for about 1-2 seconds. The other example just has a few extra lines, but it looks like it causes a huge exponential increase in complexity and freezes VS Code forever.

It would be a really good idea to add a simple timeout so that we don't accidentally freeze the editor.

These error messages from Sublime would be even better:

ERROR: Regex exhausted stack searching file
ERROR: Regex complexity too high searching file

Thanks!

[IllusionMH]

This https://twitter.com/schuay/status/1325715124930420736 looks promising for current case, but wonder if it will be applicable.

Details in Chromium bug tracker: Issue 10765: Tracking bug: Non-backtracking regexp execution