switch_root: fix double close [coverity scan]

Up on successful fdopendir(3) file descriptior that will be closed, that
happens in recursiveRemove() switch_root(8) function.

CID: 360697
Reference: https://pubs.opengroup.org/onlinepubs/9699919799/functions/fdopendir.html
Co-Author: Sami Kerola <kerolasa@iki.fi>
Signed-off-by: Karel Zak <kzak@redhat.com>
Signed-off-by: Sami Kerola <kerolasa@iki.fi>

diff --git a/sys-utils/switch_root.c b/sys-utils/switch_root.c
index a21f298dcf77f134251cd423b9ccafd3b76cb6ee..3195c789892423fddd4b861b319ce8395e2c6c3c 100644 (file)
--- a/sys-utils/switch_root.c
+++ b/sys-utils/switch_root.c
@@ -63,7 +63,6 @@ static int recursiveRemove(int fd)
 
        /* fdopendir() precludes us from continuing to use the input fd */
        dfd = dirfd(dir);
-
        if (fstat(dfd, &rb)) {
                warn(_("stat failed"));
                goto done;
@@ -104,10 +103,8 @@ static int recursiveRemove(int fd)
                                int cfd;
 
                                cfd = openat(dfd, d->d_name, O_RDONLY);
-                               if (cfd >= 0) {
-                                       recursiveRemove(cfd);
-                                       close(cfd);
-                               }
+                               if (cfd >= 0)
+                                       recursiveRemove(cfd);   /* it closes cfd too */
                                isdir = 1;
                        }
                }
@@ -117,10 +114,11 @@ static int recursiveRemove(int fd)
        }
 
        rc = 0; /* success */
-
 done:
        if (dir)
                closedir(dir);
+       else
+               close(fd);
        return rc;
 }
 
@@ -129,8 +127,7 @@ static int switchroot(const char *newroot)
        /*  Don't try to unmount the old "/", there's no way to do it. */
        const char *umounts[] = { "/dev", "/proc", "/sys", "/run", NULL };
        int i;
-       int cfd;
-       pid_t pid;
+       int cfd = -1;
        struct stat newroot_stat, sb;
 
        if (stat(newroot, &newroot_stat) != 0) {
@@ -165,43 +162,51 @@ static int switchroot(const char *newroot)
        cfd = open("/", O_RDONLY);
        if (cfd < 0) {
                warn(_("cannot open %s"), "/");
-               return -1;
+               goto fail;
        }
 
        if (mount(newroot, "/", NULL, MS_MOVE, NULL) < 0) {
-               close(cfd);
                warn(_("failed to mount moving %s to /"), newroot);
-               return -1;
+               goto fail;
        }
 
        if (chroot(".")) {
-               close(cfd);
                warn(_("failed to change root"));
-               return -1;
+               goto fail;
        }
 
        if (chdir("/")) {
-               close(cfd);
                warn(_("cannot change directory to %s"), "/");
-               return -1;
+               goto fail;
        }
 
-       pid = fork();
-       if (pid <= 0) {
+       switch (fork()) {
+       case 0: /* child */
+       {
                struct statfs stfs;
 
                if (fstatfs(cfd, &stfs) == 0 &&
                    (F_TYPE_EQUAL(stfs.f_type, STATFS_RAMFS_MAGIC) ||
                     F_TYPE_EQUAL(stfs.f_type, STATFS_TMPFS_MAGIC)))
                        recursiveRemove(cfd);
-               else
+               else {
                        warn(_("old root filesystem is not an initramfs"));
-               if (pid == 0)
-                       exit(EXIT_SUCCESS);
+                       close(cfd);
+               }
+               exit(EXIT_SUCCESS);
        }
+       case -1: /* error */
+               break;
 
-       close(cfd);
-       return 0;
+       default: /* parent */
+               close(cfd);
+               return 0;
+       }
+
+fail:
+       if (cfd >= 0)
+               close(cfd);
+       return -1;
 }
 
 static void __attribute__((__noreturn__)) usage(void)