RFR: 8261299: Use-after-free on failure path in LinuxPackage.c, getJvmLauncherLibPath

[Andy Herrick]

On Mon, 8 Feb 2021 09:05:23 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> SonarCloud instance reports a new warning after JDK-8254702:
>  "Use of memory after it is freed"
> 
> char* getJvmLauncherLibPath(void) {
>        ...
>         popenStatus = popenCommand(pkgQueryCmd, pkg->name, findLauncherLib,
>                                                         &launcherLibPath);
>         if (popenStatus) {
>             free(launcherLibPath); <---- frees here
>             goto cleanup;
>         }
>     }
> 
> cleanup:
>     free(modulePath);
>     freePackageDesc(pkg);
> 
>     return launcherLibPath; <--- here
> }
> 
> We need to null it out before returning.
> 
> Additional testing:
>  - [x] Linux x86_64 (Ubuntu) `tools/jpackage`

Marked as reviewed by herrick (Reviewer).

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PR: https://git.openjdk.java.net/jdk/pull/2453