nfs-utils - mtab locking needed on add as well as update

Hi all,

I noticed some mtab corruption the other day when doing some autofs
testing but thought nothing of it.

When investigating another issue I came across utils/mount.c:add_mtab
which looks like it adds an entry to /etc/mtab without performing
correct locking. Perhaps this is not needed when adding entries but I
think it is.

diff --git a/utils/mount/mount.c b/utils/mount/mount.c
index ca87e3d1b7fb60bc04d7e3504a7bcb4985e79b38..5e0e599578a9cad26ea12916e6c49e0c3bb99f0f 100644 (file)
--- a/utils/mount/mount.c
+++ b/utils/mount/mount.c
@@ -149,11 +149,7 @@ int add_mtab(char *fsname, char *mount_point, char *fstype, int flags, char *opt
        ment.mnt_freq = 0;
        ment.mnt_passno= 0;
 
-       if ((fd = open(MOUNTED"~", O_RDWR|O_CREAT|O_EXCL, 0600)) == -1) {
-               fprintf(stderr, "Can't get "MOUNTED"~ lock file");
-               return 1;
-       }
-        close(fd);
+       lock_mtab();
 
         if ((mtab = setmntent(MOUNTED, "a+")) == NULL) {
                fprintf(stderr, "Can't open " MOUNTED);
@@ -161,21 +157,22 @@ int add_mtab(char *fsname, char *mount_point, char *fstype, int flags, char *opt
        }
 
         if (addmntent(mtab, &ment) == 1) {
+               endmntent(mtab);
+               unlock_mtab();
                fprintf(stderr, "Can't write mount entry");
                return 1;
        }
 
         if (fchmod(fileno(mtab), 0644) == -1) {
+               endmntent(mtab);
+               unlock_mtab();
                fprintf(stderr, "Can't set perms on " MOUNTED);
                return 1;
        }
 
        endmntent(mtab);
 
-       if (unlink(MOUNTED"~") == -1) {
-               fprintf(stderr, "Can't remove "MOUNTED"~");
-               return 1;
-       }
+       unlock_mtab();
 
        return 0;
 }