Fixes in issue in the qsort comparison function #1997
Merged
+37
−241
Conversation
This file contains 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
…of large values, when cast to an int, could lead to undefined behavior (integer overflow/underflow), resulting in data errors.
jedwards4b
approved these changes
Jan 22, 2025
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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Outdated suggestions cannot be applied.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.
With 64-bit offsets, when comparing very large values found in ultra-high resolution configurations, the difference of the two iomap values can be greater than the size of a 32-bit integer, leading to undefined behavior, and causing incorrect reads.
Note that this change does technically double the instruction count for this part of the function from 3 -> 6 instructions under a couple of compilers looked at, but it didn't seem to have any practical impact on the few tests run. Submitting as-is for now, and if later more thorough tests show a performance problem, we can always do an ifdef based on type.