py/compile: Fix potential Py-stack overflow in try-finally with return.#13569
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dpgeorge merged 1 commit intomicropython:masterfrom Jan 31, 2024
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If a return is executed within the try block of a try-finally then the return value is stored on the top of the Python stack during the execution of the finally block. In this case the Python stack is one larger than it normally would be in the finally block. Prior to this commit, the compiler was not taking this case into account and could have a Python stack overflow if the Python stack used by the finally block was more than that used elsewhere in the function. In such a scenario the last argument of the function would be clobbered by the top-most temporary value used in the deepest Python expression/statement. This commit fixes that case by making sure enough Python stack is allocated to the function. Fixes issue micropython#13562. Signed-off-by: Damien George <damien@micropython.org>
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Code size report: |
Codecov ReportAll modified and coverable lines are covered by tests ✅
Additional details and impacted files@@ Coverage Diff @@
## master #13569 +/- ##
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Coverage 98.36% 98.36%
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Files 159 159
Lines 21089 21093 +4
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+ Hits 20744 20748 +4
Misses 345 345 ☔ View full report in Codecov by Sentry. |
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If a return is executed within the try block of a try-finally then the return value is stored on the top of the Python stack during the execution of the finally block. In this case the Python stack is one larger than it normally would be in the finally block.
Prior to this commit, the compiler was not taking this case into account and could have a Python stack overflow if the Python stack used by the finally block was more than that used elsewhere in the function. In such a scenario the last argument of the function would be clobbered by the top-most temporary value used in the deepest Python expression/statement.
This commit fixes that case by making sure enough Python stack is allocated to the function.
Fixes issue #13562.