The compose attachment picker and inline-image picker call
takePersistableUriPermission on every pick, but nothing ever released
those grants (releasePersistableUriPermission was absent repo-wide). The
app accumulated indefinite read access to every file/photo ever attached
and could hit the per-app persisted-grant cap — after which the take
(swallowed by runCatching) silently fails and a later draft's image
won't reload. (Post-batch security review, Low.)
The picked bytes are copied into the app cache at enqueue
(copyAttachments), so a grant is only truly needed to reload an image
when a *draft* is reopened. New AttachmentUriGrants releases a URI's
grant once no remaining draft or outbox row references it; callers invoke
it after the referencing row is gone:
- MailRepositoryImpl.deleteDraft (a deleted draft can't reopen)
- MailRepositoryImpl.cancelOutboxMessage
- SendWorker after a send succeeds, and when a queued message is dropped
because its account was removed
A URI still referenced by another live draft/outbox row is kept; a
release of a grant not actually held throws and is swallowed.
Also hardens attachment filenames: sanitizeAttachmentName strips path
separators and ISO control chars (incl. CR/LF) from picked/received
display names before they become on-disk or MIME filenames, so a crafted
name can't traverse directories or inject header lines. Applied in the
compose picker (queryFileName) and outbox/incoming staging.
Tests: pure release-decision (unreferencedUris), the filename sanitizer,
and the repository wiring (deleteDraft/cancelOutboxMessage call the
releaser with the removed row's URIs, after deleting the row).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
JMR-devandClaude Opus 4.8