core/mount: copy options before mutating in prepareIDMappedOverlay - #14204
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prepareIDMappedOverlay removed the lowerdir= entry and appended its replacement directly on the slice it received, mutating the caller's backing array. Mount.mount passes m.Options straight in without cloning, so any caller retaining a reference to the original Mount (e.g. through mount.All) observed its Options silently rewritten to the temporary idmapped lowerdir path, which is removed again once the idmap cleanup function runs. compactLowerdirOption in the same file already avoids this by copying before mutating; apply the same guard here. Signed-off-by: zanarelli <zanarelli.dev@gmail.com>
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Signed-off-by: Raphael Zanarelli <zanarelli.dev@gmail.com>
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What this PR does / why we need it
prepareIDMappedOverlayremoved thelowerdir=entry and appended its replacement directly on the slice it received, mutating the caller's backing array.Mount.mountpassesm.Optionsstraight intoprepareIDMappedOverlaywithout cloning, so any caller retaining a reference to the originalMount(for example throughmount.All) observed itsOptionssilently rewritten to the temporary idmapped lowerdir path, which is subsequently removed once the idmap cleanup function runs.compactLowerdirOptionin the same file already avoids this by copying before mutating viacopyOptions(opts); this PR applies the same defensive copy guard here.Includes regression test
TestPrepareIDMappedOverlayAliasesCallerOptionsasserting that caller options are not mutated.