Bug 246942 – Trace trap in JIT-compiled code

• Status: RESOLVED
• Resolution: FIXED
• Component: JavaScriptCore

[Samuel Groß]

The following sample triggers a SIGTRAP in JSC built from latest HEAD in debug configuration:

    function main() {
    let v0 = -256;
    do {
        function v2(v3,v4,v5) {
            const v6 = eval;
            const v8 = 16 / v5;
            function v9(v10,v11) {
                try {
                    const v12 = v9();
                } catch(v13) {
                    const v14 = [];
                    const v15 = [];
                    const v16 = v15.__proto__;
                    const v17 = v14.values;
                    const v19 = {"set":v17};
                    const v21 = Object.defineProperty(v16,1,v19);
                    function v22(v23,v24) {
                        const v25 = [];
                        let {"__proto__":v26,"constructor":v27,"length":v28,} = v25;
                        const v29 = v26 || v22;
                        const v30 = v27();
                        const v31 = v30.push(v25);
                        const v32 = v30.push(v29);
                    }
                    const v33 = v22();
                } finally {
                }
            }
            const v34 = v9();
            let v35 = [v8];
            const v36 = --v35;
            const v37 = v0++;
        }
        const v38 = "bigint";
        const v39 = v2();
    } while (v0 !== 8);
    gc();
    }
    main();
    // CRASH INFO
    // ==========
    // TERMSIG: 5
    // STDERR:
    // STDOUT:
    // ARGS: ./jsc/jsc --validateOptions=true --thresholdForJITSoon=10 --thresholdForJITAfterWarmUp=10 --thresholdForOptimizeAfterWarmUp=100 --thresholdForOptimizeAfterLongWarmUp=100 --thresholdForOptimizeSoon=100 --thresholdForFTLOptimizeAfterWarmUp=1000 --thresholdForFTLOptimizeSoon=1000

The crash happens in JIT-compiled code, so this may be a sign of a condition that was not expected to happen by the compiler. As this may have security implications, I'm filing this as a security issue.

[Radar WebKit Bug Importer]

<rdar://problem/101496803>

[David Degazio]

Pull request: https://github.com/WebKit/WebKit/pull/5973

[EWS]

Committed 256197@main (5faa0d3ac693): <https://commits.webkit.org/256197@main>

Reviewed commits have been landed. Closing PR #5973 and removing active labels.