Libc: zero sysctl buffer before strncpy

The uname utility from coreutils needs its read buffer zero-terminated,
regardless of read length.

Fix #2657

repos/libports/src/lib/libc/sysctl.cc

@@ -90,6 +90,8 @@ extern "C" int __sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp,
 	if (namelen != 2) return Libc::Errno(ENOENT);
 	if (index_a >= CTL_MAXID) return Libc::Errno(EINVAL);
 
+	Genode::memset(buf, 0x00, *oldlenp);
+
 	switch(index_a) {
 	case CTL_KERN:
 		if (index_b >= KERN_MAXID) return Libc::Errno(EINVAL);

repos/ports/run/noux_uname.run

@@ -1,5 +1,11 @@
-build { core init drivers/timer noux/minimal
-        lib/libc_noux noux-pkg/coreutils }
+build {
+	core init
+	app/sequence
+	drivers/timer
+	lib/libc_noux
+	noux/minimal
+	noux-pkg/coreutils
+}
 
 create_boot_directory
 
@@ -18,13 +24,16 @@ install_config {
 		<default-route>
 			<any-service> <any-child/> <parent/> </any-service>
 		</default-route>
+		<default caps="256"/>
 		<start name="timer">
 			<resource name="RAM" quantum="1M"/>
 			<provides><service name="Timer"/></provides>
 		</start>
+		<start name="sequence">
+			<resource name="RAM" quantum="16M"/>
+			<config>
 				<start name="spoof">
 					<binary name="noux"/>
-			<resource name="RAM" quantum="16M"/>
 					<config verbose="yes" stdin="/null" stdout="/log" stderr="/log">
 						<fstab>
 							<null/> <log/>
@@ -50,15 +59,23 @@ install_config {
 					</config>
 				</start>
 			</config>
+		</start>
+	</config>
 }
 
 build_boot_image {
-	core init timer ld.lib.so noux libc.lib.so libm.lib.so posix.lib.so
-	libc_noux.lib.so coreutils.tar
+	core init ld.lib.so
+	coreutils.tar
+	libc_noux.lib.so
+	libm.lib.so
+	noux libc.lib.so
+	posix.lib.so
+	sequence
+	timer
 }
 
 append qemu_args " -nographic -serial mon:stdio "
 
 # coreutils.tar is really huge when built for x86_64
 
-run_genode_until {child "noux" exited with exit value 0.*\n} 30
+run_genode_until {child "sequence" exited with exit value 0.*\n} 30