fsck: fix permissions of the temp fs image when a sandbox is used

My dev environment skips the osutil_linux sandbox because it doesn't
have a "syzkaller" user and group. The CI environment also skips the
sandbox because it sets the "CI" environment variable.

Therefore, nothing caught that, when run in the syzbot docker container,
(which has a "syzkaller" user) the sandbox actually starts to be used
and breaks fsck commands.

Syz-manager, which is run as root, writes the image to /tmp/1234.img
with permissions 0600 and then tries to run fsck under the "syzkaller"
user which doesn't have read permissions on the file, so fsck fails:

    fsck.ext4 -n exited with status code 8
    e2fsck 1.47.0 (5-Feb-2023)
    fsck.ext4: Permission denied while trying to open /tmp/1234.img
    You must have r/o access to the filesystem or be root

Changing the owner of the file to the "syzkaller" user before attempting
to run fsck under that user fixes the problem.

0 files changed, 0 insertions, 0 deletions