[release/8.0-staging] Move a lock to protect m_pDynamicStaticsInfo #97352
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
ghost
added
the
- Remove race condition where it is possible that an updated dynamic statics info pointer is published without ensuring that the data is also considered written. - Use VolatileLoadWithoutBarrier at the read site (where locks are not taken) to ensure that there are no difficult to examine reads of this pointer.
davidwrighton
added
the
Servicing-consider
jkotas
approved these changes
Jan 23, 2024
jeffschwMSFT
approved these changes
Jan 23, 2024
Member
jeffschwMSFT
left a comment
jeffschwMSFT
left a comment
There was a problem hiding this comment.
approved. we will take for consideration in 8.0.x
rbhanda
added
Servicing-approved
Member
|
@davidwrighton is this ready to merge? it is marked draft |
Member
|
Yes this is ready to merge. |
Sign up for free
to subscribe to this conversation on GitHub.
Already have an account?
Sign in.
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Outdated suggestions cannot be applied.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.
Backport of #95769 and #97353 to release/8.0-staging
/cc @davidwrighton @HJLeee
Customer Impact
This fault causes the .NET runtime to seg fault accessing a NULL pointer on startup when reading or writing the value of a static variable. The expected behavior is that access to the static variable will succeed. The customer did not report this bug with an issue, instead they filed PR #95769 to fix the issue. Internally this was also reported by a high scale service which has just been updated to use .NET 8. In addition, while looking at the internal repro, I found a different race condition that appeared to be possible, and was also fixable by the addition of a VolatileStore/VolatileLoadWithoutBarrier pair of commands (PR #97353).
Regression
This is not a regression, but issues of this form were not seen with .NET 6 or 7 on previous versions of the internal high scale service. It is possible that some pre-existing locking contention was present that was fixed in .NET 8.
Testing
This is a race condition deep in the runtime at this time, we have no means to provide effective testing on this.
Risk
Low. This fix takes code which is using a series of interlocked and volatile operations which did not correct address the possible race conditions to using a simple lock to protect the identified issue.
IMPORTANT: If this backport is for a servicing release, please verify that:
The PR target branch is
release/X.0-staging, notrelease/X.0.If the change touches code that ships in a NuGet package, you have added the necessary package authoring and gotten it explicitly reviewed.