GeezerVison is showing github.com — [3.15] gh-160708: Use the type size for resized ctypes simple objects (GH-160720) by iamsaugatpandey · Pull Request #161806 · python/cpython
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iamsaugatpandey
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Nov 11, 2026
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After ctypes.resize(), a simple object's buffer is larger than its
type. bool() and passing the object to a foreign function still used
the buffer size, so bool() read past a 16-byte string literal and the
call copied the whole buffer into the fixed-size PyCArgObject value,
corrupting the heap.
Use the type's size instead, like the value getter does since
gh-159739. bool() now checks the value's bytes directly, which also
covers simple types larger than 16 bytes such as c_longdouble_complex
on x86-64.
(cherry picked from commit 44579b0)
Co-authored-by: Saugat Pandey [email protected]
Co-authored-by: Peter Bierma [email protected]
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…bjects (pythonGH-160720)
After ctypes.resize(), a simple object's buffer is larger than its
type. bool() and passing the object to a foreign function still used
the buffer size, so bool() read past a 16-byte string literal and the
call copied the whole buffer into the fixed-size PyCArgObject value,
corrupting the heap.
Use the type's size instead, like the value getter does since
pythongh-159739. bool() now checks the value's bytes directly, which also
covers simple types larger than 16 bytes such as c_longdouble_complex
on x86-64.
(cherry picked from commit 44579b0)
Co-authored-by: Saugat Pandey <[email protected]>
Co-authored-by: Peter Bierma <[email protected]>
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