[3.3] Fix use-after-free when resizing exivars#13638
Merged
nagachika merged 1 commit intoruby:ruby_3_3from Jul 19, 2025
Merged
Conversation
[Bug #21438] Previously GC could trigger a table rebuild of the generic ivar st_table in the middle of calling the st_update callback. This could cause entries to be reallocated or rearranged and the update to be for the wrong entry. This commit adds an assertion to make that case easier to detect, and replaces the st_update with a separate st_lookup and st_insert. Also free after insert in generic_ivar_set_shape_ivptr Previously we were performing a realloc and then inserting the new value into the table. If the table was flagged as requiring a rebuild, this could trigger GC work and marking within that GC could access the ivptr freed by realloc. Co-authored-by: Aaron Patterson <tenderlove@ruby-lang.org> Co-authored-by: Jean Boussier <byroot@ruby-lang.org>
ad633be to
ae06d7f
Compare
nagachika
approved these changes
Jul 19, 2025
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
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
4 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Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be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.
[Bug #21438]
Ref: https://bugs.ruby-lang.org/issues/21438
Backport of #13635 and #13589.
Previously GC could trigger a table rebuild of the generic ivar st_table in the middle of calling the st_update callback.
This could cause entries to be reallocated or rearranged and the update to be for the wrong entry.
This commit adds an assertion to make that case easier to detect, and replaces the st_update with a separate st_lookup and st_insert.
Also free after insert in generic_ivar_set_shape_ivptr
Previously we were performing a realloc and then inserting the new value into the table.
If the table was flagged as requiring a rebuild, this could trigger GC work and marking within that GC could access the ivptr freed by realloc.