REDHAT-BUG-2537812: Command Injection

A command injection flaw was found in rpm. The macro engine's %() construct executes an embedded shell command via popen() whenever the macro text is expanded, regardless of where that text came from (rpmio/macro.cc: case '(' at :1678 calls doShellEscape(), which ends in popen(buf, "r") at :499). Installing or rebuilding a .src.rpm routes through rpmInstallSourcePackage(), whose getFiles() calls rpmRelocateSrpmFileList() (lib/relocation.cc:454); that function builds the destination path for every source and spec file with rpmGenPath(rootDir, "%{specdir}"|"%{sourcedir}", bn), and joinpath() (rpmio/rpmfileutil.cc:463) macro-expands each path component individually, including the package-supplied basename bn. A source or spec basename containing a %(cmd) construct is therefore expanded and the embedded command executed. This install path never calls rpmtsRun(), so %pkgverifylevel provides no protection: rpmReadPackageFile() hard-codes vfylevel to 0 (lib/package.cc:315) and accepts a completely unsigned .src.rpm under the distro-default policy, and rpm -i still reports success (exit 0) with nothing to indicate a command ran. rpmbuild --rebuild reaches the same relocation code during install, before any mock/chroot sandbox boundary. This was confirmed by reproducing the reporter's proof of concept with an AddressSanitizer-instrumented build of rpm at both rpm-6.1.0-release and master: rpm -i against a crafted, unsigned .src.rpm silently ran an embedded canary command while the install still exited 0, including with %pkgverifylevel all set, which shows signature policy is not the gate; negative controls (removing the leading %, or using rpm -qpl instead of installing) did not execute the command.