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Re: [PATCH v3] Fix reuse of va_list object in while loop in _nc_printf_s
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From: |
Thomas Dickey |
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Subject: |
Re: [PATCH v3] Fix reuse of va_list object in while loop in _nc_printf_string_sp() |
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Date: |
Wed, 27 Sep 2023 18:10:13 -0400 |
On Wed, Sep 27, 2023 at 06:09:50PM +0100, Ian Abbott wrote:
> When `#if USE_SAFE_SPRINTF` is false and `#if HAVE_VSNPRINTF` is true,
> `vsnprintf()` is called in a `while` loop that reallocates the
> `my_buffer` if the buffer is too small to hold the output.
>
> The `va_list ap` parameter value becomes indeterminate after the first
> call to `vsnprintf()` leading to undefined behavior on the next
> iteration of the loop. Make a fresh copy of the `va_list ap` parameter
> into new variable `va_list ap2` and pass the copy to `vsnprintf()`.
thanks
--
Thomas E. Dickey <dickey@invisible-island.net>
https://invisible-island.net
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