Fix: Possible Vulnerability in zlib Library #4809
Open
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
inftrees.c was subtracting an offset from a pointer to an array, in order to provide a pointer that allowed indexing starting at the offset. This is not compliant with the C standard, for which the behavior of a pointer decremented before its allocated memory is undefined. Per the recommendation of a security audit of the zlib code by Trail of Bits and TrustInSoft, in support of the Mozilla Foundation, this tiny optimization was removed, in order to avoid the possibility of undefined behavior.
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Outdated suggestions cannot be applied.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.
Issue Details
The function inflate_table9() in this repository is nearly identical to inflate_table() from zlib.
The original function was patched due to a vulnerability identified in madler/zlib@6a04314.
The same issue exists in this repository's function but remains unpatched.
Proposed Fix
This PR applies the same patch as the one in zlib to eliminate the vulnerability.
References
CVE: CVE-2016-9840
Original Fix: Original Fix