In the Linux kernel, the following vulnerability has been resolved:
ceph: fix oops due to invalid pointer for kfree() in parse_longname()
This fixes a kernel oops when reading ceph snapshot directories (.snap),
for example by simply running `ls /mnt/my_ceph/.snap`.
The variable str is guarded by __free(kfree), but advanced by one for
skipping the initial '_' in snapshot names. Thus, kfree() is called
with an invalid pointer. This patch removes the need for advancing the
pointer so kfree() is called with correct memory pointer.
Steps to reproduce:
1. Create snapshots on a cephfs volume (I've 63 snaps in my testcase)
2. Add cephfs mount to fstab
$ echo "samba-fileserver@.files=/volumes/datapool/stuff/3461082b-ecc9-4e82-8549-3fd2590d3fb6 /mnt/test/stuff ceph acl,noatime,_netdev 0 0" >> /etc/fstab
3. Reboot the system
$ systemctl reboot
4. Check if it's really mounted
$ mount | grep stuff
5. List snapshots (expected 63 snapshots on my system)
$ ls /mnt/test/stuff/.snap
Now ls hangs forever and the kernel log shows the oops.
