libartifact: take store lock in extract and mount paths code - #1085
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goyaladitya05 wants to merge 1 commit into
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libartifact: take store lock in extract and mount paths code#1085goyaladitya05 wants to merge 1 commit into
goyaladitya05 wants to merge 1 commit into
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Signed-off-by: Aditya Goyal <goyaladitya2403@gmail.com>
goyaladitya05
marked this pull request as ready for review
August 16, 2026 10:57
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BlobMountPaths(), Extract() and ExtractTarStream() call getArtifactAndImageSource() without holding the store lock, even though it requires one: it reads index.json via lookupArtifactLocked() and NewImageSource(). A concurrent add or remove rewriting index.json can cause these readers to fail or see inconsistent data. The problem was marked with
FIX ME / LOCKING BUGcomments in #522.Take the read lock around the getArtifactAndImageSource() call and document the locking contract on the helper. The lock is deliberately not held while blob contents are read: blobs are content addressed and immutable, so a concurrent removal can at most cause a read to fail, never return wrong data. Holding the lock for the whole operation would block all writers for the duration of a potentially large extraction (or a slow client in the tar stream case) - the same tradeoff Add() already makes by unlocking around blob copying.
The write-side race in Add() (#483) is a separate problem and not addressed here.
Ref: podman-container-tools/podman#27264