skia2/tests/sksl/shared/Ossfuzz37677.metal
John Stiles bb8cf5804c Fix invalid variable ref-kind discovered by fuzzer.
No-op arithmetic simplification will convert expressions like `x += 0`
to `x`. When making this simplification, we will also downgrade the ref-
kind of `x` from "write" to "read" since the new expression is no longer
an assignment.

The fuzzer discovered that the ref-kind downgrade was too aggressive,
and would also traverse into nested subexpressions and downgrade them
as well. That is, for `x[y=z] += 0` would convert both `x` and `y`
into "read" references, which is incorrect; `y` is still being written
to.

The fuzzer managed to turn this mistake into an assertion by leveraging
a separate optimization. It added a leading, side-effect-less comma
expression for us to detect as worthless and eliminate. In doing so, we
clone the expression with the busted ref-kind, triggering an assertion.

Change-Id: I42fc31f6932f679ae875e2b49db2ad2f4e89e2cb
Bug: oss-fuzz:37677
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/442536
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
2021-08-27 14:01:21 +00:00

22 lines
524 B
Metal

#include <metal_stdlib>
#include <simd/simd.h>
using namespace metal;
struct Uniforms {
float4 colorGreen;
};
struct Inputs {
};
struct Outputs {
float4 sk_FragColor [[color(0)]];
};
fragment Outputs fragmentMain(Inputs _in [[stage_in]], constant Uniforms& _uniforms [[buffer(0)]], bool _frontFacing [[front_facing]], float4 _fragCoord [[position]]) {
Outputs _out;
(void)_out;
array<int, 1> x;
int y = 0;
int z = 0;
x[y = z];
_out.sk_FragColor = _uniforms.colorGreen;
return _out;
}