<regex>: Handle overflow and allocation failure when parsing repetitions
#5716
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
StephanTLavavej
added
bug
StephanTLavavej
approved these changes
Sep 17, 2025
|
Thanks for noticing these subtle problems and clearly explaining them! 😻 |
|
I'm mirroring this to the MSVC-internal repo - please notify me if any further changes are pushed. |
|
Thanks for noticing and fixing these corner cases! 🦅 👁️ 🛠️ |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This fixes two obscure bugs when parsing repetitions:
_Loopscounter can potentially overflow, which will result in a crash during matching. The fix is to throw aregex_error(of suitable typeerror_space) when overflow is about to occur during parsing._Node_end_repobject can potentially be leaked if the subsequentnew _Node_rep(...)throws an exception. The simplest fix is to link the_Node_end_repobject into the NFA before allocating and constructing the_Node_repobject, so the_Node_end_repobject will be cleaned up together with the rest of the NFA by the_Tidy_guardin_Parser2::_Compileif an exception occurs.No test coverage added because testing these bugs is impractical. In particular, the first bug occurs only after more than 500 GB have been allocated to represent the NFA.