[common_callbacks] fix make_confirmation_callback lifetime issue #4004
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The make_confirmation_callback function takes the key argument as const ref, meaning that it'll be bound to an existing QString when the arg is QString, but a temporary QString would be constructed and bound to it when the "key" is not a QString. This is fine during the make_confirmation_callback's scope since const& extend the lifetime of the temporary, but passing that "const&" to a capture list of a lambda that'll be executed later does not extend the lifetime, hence leading to undefined behavior. The patch fixes this issue by taking QString as a value and moving that into the lambda capture. Signed-off-by: Mustafa Kemal Gilor <mustafa.gilor@canonical.com>
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Additional details and impacted files@@ Coverage Diff @@
## main #4004 +/- ##
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Coverage 89.27% 89.27%
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Lines 14653 14653
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Good work, thanks for catching this. |
georgeliao
approved these changes
Mar 26, 2025
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Thanks for the prompt review @georgeliao @Sploder12 ! |
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The make_confirmation_callback function takes the key argument as const ref, meaning that it'll be bound to an existing QString when the arg is QString, but a temporary QString would be constructed and bound to it when the "key" is not a QString. This is fine during the make_confirmation_callback's scope since const& extend the lifetime of the temporary, but passing that "const&" to a capture list of a lambda that'll be executed later does not extend the lifetime, hence leading to undefined behavior.
I believe this was not causing any issues in release builds because of the optimization level. The compiler is probably inlining the whole thing, so the QString is directly constructed into the lambda's body. I could only trigger this while running the unit tests in Windows, built with the Debug configuration.
The patch fixes this issue by taking QString as a value and moving that into the lambda capture.
MULTI-1907