Fix problems in parsing the kernel command line

The kernel command line allows quoted strings with whitespace in them. Until now,
such parameters would crash /init and cause a kernel panic.
Move parsing into a function and use the 'set' builtin to split /proc/cmdline
into arguments.

Fixes FS#13900 and FS#22080.

2 files changed, 27 insertions, 23 deletions

diff --git a/init b/init
index d79dd3d..e230f82 100644
--- a/init
+++ b/init
@@ -19,8 +19,6 @@ else
 fi
 /bin/mount -t tmpfs run /run -o nosuid,noexec,nodev,mode=1777,size=10M
 
-read CMDLINE </proc/cmdline
-
 root=""
 init=""
 echo "/sbin/modprobe" > /proc/sys/kernel/modprobe
@@ -28,27 +26,8 @@ echo "/sbin/modprobe" > /proc/sys/kernel/modprobe
 # set default mount handler
 mount_handler="default_mount_handler"
 
-for cmd in ${CMDLINE}; do
-    case "${cmd}" in
-        \#*) break ;; # ignore everything after a # in the commandline
-        # The kernel passes those to the kernel on its own
-        [0123456Ss]) ;;
-        [0-9]*) ;;
-        single) ;;
-        rw) readwrite="yes" ;;
-        ro) readwrite="no" ;;
-        # only export stuff that does work with ash :)
-        *=*) rhs="$(echo "${cmd}" | cut -d= -f2-)"
-             cmd="$(echo "${cmd}" | cut -d= -f1 | sed 's|\.|_|g')"
-             cmd="$(echo "${cmd}" | sed 's|-|_|g')=\"${rhs}\""
-             (echo "${cmd}" | grep -qe '^[0-9]') || eval "${cmd}"
-             ;;
-        *)   cmd="$(echo "${cmd}" | sed 's|\.|_|g')"
-             cmd="$(echo "${cmd}" | sed 's|-|_|g')"
-             (echo "${cmd}" | grep -qe '^[0-9]') || eval "${cmd}=y"
-             ;;
-    esac
-done
+# parse the kernel command line
+parse_cmdline
 
 # if available, start udevd at this stage
 if [ -x /sbin/udevd ]; then
diff --git a/init_functions b/init_functions
index a42d257..fd5bbb6 100644
--- a/init_functions
+++ b/init_functions
@@ -30,6 +30,31 @@ launch_interactive_shell() {
     /bin/sh -i
 }
 
+parse_cmdline() {
+    eval set -- $(cat /proc/cmdline)
+    for cmd in "$@"; do
+        case "${cmd}" in
+            \#*) break ;; # ignore everything after a # in the commandline
+            # The kernel passes those to the kernel on its own
+            [0123456Ss]) ;;
+            [0-9]*) ;;
+            single) ;;
+            rw) readwrite="yes" ;;
+            ro) readwrite="no" ;;
+            # only export stuff that does work with ash :)
+            *=*) rhs="$(echo "${cmd}" | cut -d= -f2-)"
+                cmd="$(echo "${cmd}" | cut -d= -f1 | sed 's|\.|_|g')"
+                cmd="$(echo "${cmd}" | sed 's|-|_|g')=\"${rhs}\""
+                (echo "${cmd}" | grep -qe '^[0-9]') || eval "${cmd}"
+                ;;
+            *)  cmd="$(echo "${cmd}" | sed 's|\.|_|g')"
+                cmd="$(echo "${cmd}" | sed 's|-|_|g')"
+                (echo "${cmd}" | grep -qe '^[0-9]') || eval "${cmd}=y"
+                ;;
+        esac
+    done
+}
+
 default_mount_handler() {
     if [ ${root:0:5} != "/dev/" ] || ! poll_device "${root}" ${rootdelay}; then
         msg "Root device '${root}' doesn't exist. Attempting to create it."