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Fix race condition in concurrent artifact additions #483

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Fix race condition in concurrent artifact additions #483

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19 changes: 7 additions & 12 deletions common/pkg/libartifact/store/store.go
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Original file line number Diff line number Diff line change
Expand Up @@ -218,13 +218,8 @@ func (as ArtifactStore) Add(ctx context.Context, dest string, artifactBlobs []li
return nil, errors.New("append option is not compatible with type option")
}

locked := true
as.lock.Lock()
defer func() {
if locked {
as.lock.Unlock()
}
}()
defer as.lock.Unlock()

// Check if artifact already exists
artifacts, err := as.getArtifacts(ctx, nil)
Expand Down Expand Up @@ -297,10 +292,11 @@ func (as ArtifactStore) Add(ctx context.Context, dest string, artifactBlobs []li
}
defer imageDest.Close()

// Unlock around the actual pull of the blobs.
// This is ugly as hell, but should be safe.
locked = false
as.lock.Unlock()
// Keep the lock held during blob copying to prevent concurrent artifact adds
// from racing on the OCI layout index file. The lock was previously released
// here as an optimization, but this created a race condition where concurrent
// artifact additions could overwrite each other's index entries.
// See: https://github.com/containers/podman/issues/27569

// ImageDestination, in general, requires the caller to write a full image; here we may write only the added layers.
// This works for the oci/layout transport we hard-code.
Expand Down Expand Up @@ -356,8 +352,7 @@ func (as ArtifactStore) Add(ctx context.Context, dest string, artifactBlobs []li
artifactManifest.Layers = append(artifactManifest.Layers, newLayer)
}

as.lock.Lock()
locked = true
// Lock is still held from the beginning of the function
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@mtrmac mtrmac Nov 21, 2025

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This comment does not make much sense stand-alone for future readers of the code, without seeing it in this diff.


rawData, err := json.Marshal(artifactManifest)
if err != nil {
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