subsequent setlocale call resets pointer causing memory access violation #276
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matejbrumen
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Nov 14, 2022
- Replace char* with std::string to persist the memory content and avoid memory access violation when restoring old locale - Second call to setlocale frees the old_lc_time pointer which causes the memory access violation during restore (3rd call)
mloskot
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Nov 15, 2022
* #276 Fix memory access violation when parsing datetime types - Replace char* with std::string to persist the memory content and avoid memory access violation when restoring old locale - Second call to setlocale frees the old_lc_time pointer which causes the memory access violation during restore (3rd call) * Fix possibility of dereferencing nullptr when assigning C String to std::string - C strings can be null
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Environment
Actual behavior
In nanodbc::result::result_impl::get_ref_impl<T,type> for SQL_C_DATE, SQL_C_TIME, SQL_C_TIMESTAMP std::setlocale is used incorrectly resulting in a memory access violation.
....
char* old_lc_time = std::setlocale(LC_TIME, nullptr); <- this returns pointer to current locale
std::setlocale(LC_TIME, ""); <- subsequent call here deletes memory referenced by old_lc_time
....
std::setlocale(LC_TIME, old_lc_time); <- memory access violation due to invalid old_lc_time pointer
Expected behavior
Minimal Working Example
This can be fixed by taking a copy of string pointed to by old_lc_time before subsequent call to setlocale with "". This way it is a copy on the stack.
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