gh-88116: Avoid undefined behavior when decoding varints in code objects #94375
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
…e objects
It seems like we'll fail to correctly decode a varint between INT_MAX
and UINT_MAX or if a signed varint is > INT_MAX / 2 or < INT_MIN / 2 as
this is written today. In fact, it might left shift a 1 into the sign
bit, which would be UB.
Indeed, this test program shows the issue:
```
int main()
{
int val = 2147483647;
unsigned int shift = 1;
std::cout << (val << shift) << std::endl;
}
```
As this prints -2.
markshannon
approved these changes
Jun 28, 2022
|
Thanks @pablogsal for the PR 🌮🎉.. I'm working now to backport this PR to: 3.11. |
miss-islington
pushed a commit
to miss-islington/cpython
that referenced
this pull request
Jun 28, 2022
…e objects (pythonGH-94375) (cherry picked from commit c485ec0) Co-authored-by: Pablo Galindo Salgado <Pablogsal@gmail.com>
|
GH-94387 is a backport of this pull request to the 3.11 branch. |
gvanrossum
pushed a commit
to gvanrossum/cpython
that referenced
this pull request
Jun 30, 2022
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Outdated suggestions cannot be applied.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.
It seems like we'll fail to correctly decode a varint between INT_MAX
and UINT_MAX or if a signed varint is > INT_MAX / 2 or < INT_MIN / 2 as
this is written today. In fact, it might left shift a 1 into the sign
bit, which would be UB.
Indeed, this test program shows the issue:
As this prints -2.