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[SIL] Fix use-after-free in SILFunction::print. #29949

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Merged
merged 1 commit into from
Feb 21, 2020
Merged

[SIL] Fix use-after-free in SILFunction::print. #29949

merged 1 commit into from
Feb 21, 2020

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dan-zheng
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@dan-zheng dan-zheng commented Feb 20, 2020 •
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Fix use-after-free in helper function printSILFunctionNameAndType.
The address of a DenseMap local variable was used after the function returned.

Resolves SR-12239.

@dan-zheng
[SIL] Fix use-after-free in SILFunction::print.
5efe73f 
Fix use-after-free in helper function `printSILFunctionNameAndType`.
The address of a `DenseMap` local variable is used after the function returns.

Resolves SR-12239.
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@swift-ci Please smoke test

varungandhi-apple
varungandhi-apple approved these changes Feb 20, 2020
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Thanks, LGTM. Could you briefly describe your debugging process/how you got the reduced test case? Did you use ASan [or run into any troubles using ASan]?

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dan-zheng commented Feb 20, 2020 •
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Could you briefly describe your debugging process/how you got the reduced test case? Did you use ASan [or run into any troubles using ASan]?

I followed reproducer instructions at SR-12239 and found that the crash occurred during stdlib compilation for a specific function: _withContiguousStorage in stdlib/public/core/Diffing.swift. Diffing.swift was a single file reproducer. I manually minimized it to three lines.

I just used print debugging, nothing fancy - the buggy code was familiar to me since I wrote it. Sorry for introducing the bug!

I actually haven't used ASan for debugging Swift. I'm not sure how exactly to apply it here.

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I'm not sure how exactly to address #29949 (comment): making the added test an ASAN test.

I'll merge this PR now to unblock progress, since I ran into SR-12239 independently. Happy to address feedback later.

@dan-zheng dan-zheng merged commit 9600b97 into swiftlang:master Feb 21, 2020
@dan-zheng dan-zheng deleted the SR-12239 branch February 21, 2020 01:53
@dan-zheng dan-zheng mentioned this pull request May 4, 2020
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