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Fix UB from out-of-range <stretch>

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If there was a scaling mode value (serialized in the XML as <stretch>
for legacy reasons) that was not 0 or 1 or 2, then the rectangle with
the stretch information would not be initialized by get_stretch_info,
which would lead to a crash, either from dividing by zero (most likely)
or from reading an uninitialized value.

To fix this, when reading <stretch>, normalize it to a sane default if
the value is otherwise bogus. And for good measure, an assertion is
added in get_stretch_info() if the value is still somehow bogus.

Fixes #1155.
This commit is contained in:
Misa 2024-03-29 20:16:57 -07:00
parent 8640ead937
commit 217996b134
2 changed files with 14 additions and 1 deletions
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8
desktop_version/src/Game.cpp
View file

@ -4728,7 +4728,13 @@ void Game::deserializesettings(tinyxml2::XMLElement* dataNode, struct ScreenSett
if (SDL_strcmp(pKey, "stretch") == 0) if (SDL_strcmp(pKey, "stretch") == 0)
{ {
screen_settings->scalingMode = help.Int(pText); int mode = help.Int(pText);
if (mode < 0 || mode >= NUM_SCALING_MODES)
{
/* Pick a sane default. */
mode = SCALING_INTEGER;
}
screen_settings->scalingMode = mode;
} }
if (SDL_strcmp(pKey, "useLinearFilter") == 0) if (SDL_strcmp(pKey, "useLinearFilter") == 0)

7
desktop_version/src/Graphics.cpp
View file

@ -3517,6 +3517,13 @@ void Graphics::get_stretch_info(SDL_Rect* rect)
rect->w = width; rect->w = width;
rect->h = height; rect->h = height;
break; break;
default:
SDL_assert(0 && "Invalid scaling mode!");
/* Width and height should be nonzero to avoid division by zero. */
rect->x = 0;
rect->y = 0;
rect->w = width;
rect->h = height;
} }
} }