Fix incorrect file permissions of vmcore-dmesg-incomplete.txt

vmcore-dmesg-incomplete.txt is generated by shell redirection,
which taking the default umask value. When dmesg collector exits
with non-zero, the file will exist and anyone can have access to
it.

This patch fixed the issue by chmod the file, making it accessible
only to its owner.

Signed-off-by: Tao Liu <ltao@redhat.com>
Acked-by: Kairui Song <kasong@redhat.com>

kdump-lib-initramfs.sh

@@ -188,6 +188,9 @@ save_vmcore_dmesg_fs() {
         sync
         dinfo "saving vmcore-dmesg.txt complete"
     else
+        if [ -f ${_path}/vmcore-dmesg-incomplete.txt ]; then
+            chmod 600 ${_path}/vmcore-dmesg-incomplete.txt
+        fi
         derror "saving vmcore-dmesg.txt failed"
     fi
 }