dlopen: make error handling thread safe #431
Merged
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
The dlerror() value is stored in thread local storage and thus checking the error from go code is not safe because go can schedule goroutines on any other thread at any time. This means it is possible that between the dlsym() or dlclose() call the code get moved to another thread and thus the dlerror() value is not what we expect. Instead because we read now from another thread it will be an error from a different call. A test is added which without this fix is able to reproduce the problem somewhat reliably. This issue was observed in the podman CI[1] which uses the sdjournal API. [1] containers/podman#20569 Signed-off-by: Paul Holzinger <pholzing@redhat.com>
|
Example failure with the new test but without the locked thread: |
cgwalters
approved these changes
Nov 3, 2023
|
Thanks for the quick review/merge @cgwalters |
|
Nice digging on this! |
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Outdated suggestions cannot be applied.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.
The dlerror() value is stored in thread local storage and thus checking the error from go code is not safe because go can schedule goroutines on any other thread at any time. This means it is possible that between the dlsym() or dlclose() call the code get moved to another thread and thus the dlerror() value is not what we expect. Instead because we read now from another thread it will be an error from a different call.
A test is added which without this fix is able to reproduce the problem somewhat reliably.
This issue was observed in the podman CI[1] which uses the sdjournal API.
[1] containers/podman#20569