SILGen: Fix potential use-after-free in @_backDeploy coroutines
#60021
Conversation
The SIL verifier has identified an issue with the SIL generated for property accessors structured like this:
```
public struct S {
@available(macOS, introduced: 12.0)
@_backDeploy(before: macOS 13.0)
public var x: String {
_read {
yield "x"
}
}
}
```
The emitted SIL is invalid because the value `%9` is used after `end_apply` may have ended the lifetime of the value:
```
bb1:
%8 = function_ref @$s4test1SV1xSSvrTwB : $@yield_once @convention(method) (S) -> @yields @guaranteed String9
(%9, %10) = begin_apply %8(%0) : $@yield_once @convention(method) (S) -> @yields @guaranteed String
end_apply %10
yield %9 : $String, resume bb3, unwind bb2
```
The fix is to move the `end_apply` to the resume and unwind blocks, after the value has been yielded to the caller.
Resolves rdar://96879247
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@swift-ci please smoke test |
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I am not reviewing this... but unless the test that you modified has this specific test there, you aren't actually testing the broken test case? If my guess is right, can you dd that test case explicitly and check the SILGen? |
The changed location of I am not sure whether the fact that the verifier didn't catch this on this existing test case is a bug in the verifier or not. It seems like the lifetime of |
Yes, I think that's a good idea. You can do that in a follow-up PR. These kind of lifetime/ownership verifications are only done for non-trivial types. So if you use e.g. a class in your test, it should work. |
…lds a non-trivial value. This is a follow up to swiftlang#60021 to ensure that a test exists that would cause lifetime verification to fail if the fix regressed.
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I've expanded the runtime tests for |
…lds a non-trivial value. This is a follow up to swiftlang#60021 to ensure that a test exists that would cause lifetime verification to fail if the fix regressed.
…lds a non-trivial value. This is a follow up to swiftlang#60021 to ensure that a test exists that would cause lifetime verification to fail if the fix regressed.
The SIL verifier has identified an issue with the SIL generated for property accessors structured like this:
The emitted SIL is invalid because the value
%9is used afterend_applymay have ended the lifetime of the value:The fix is to move the
end_applyto the resume and unwind blocks, after the value has been yielded to the caller.Resolves rdar://96879247