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Fix memory unsafety in FontDescription::set_family_static
#186
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This commit fixes a memory safety issue in this method. `<str as ToGlibPtr>::to_glib_none` returns a null-terminated string which only lives as long as the `Stash` it returns. This leads to use-after-free because `pango_font_description_set_family_static` expects the given string to outlive this `PangoFontDescription`. Obviously, we can't simply pass the value of `str::as_ptr` because it might not be null-terminated. What we need is `&'static CStr` - `CStr` guarantees the memory representation of the string is null-terminated, and `&'static` guarantees it will remain valid throughout the program's lifetime.
sdroege
reviewed
May 11, 2020
src/font_description.rs
Outdated
| use FontDescription; | ||
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| impl FontDescription { | ||
| pub fn set_family_static(&mut self, family: &'static str) { | ||
| pub fn set_family_static(&mut self, family: &'static CStr) { |
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This is rather annoying to use like that. I'd suggest removing the function completely as it doesn't bring much advantage.
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It's impossible to make it as ergonomic as other methods. I would have no problem with it being removed.
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Let's get rid of it then, if someone wants to call it they can still use the FFI functions.
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@yvt do you want to update the PR?
We decided to get rid of this method because it was deemed too unergonomic to use.
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@GuillaumeGomez All green |
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Thanks! |
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It's illegal to pass the result of
<str as ToGlibPtr>::to_glib_none()to a*_staticfunction because it expires at the end of the statement.