fs/ntfs3: Fix NULL deref in ntfs_update_mftmirr

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: Fix NULL deref in ntfs_update_mftmirr If ntfs_fill_super() wasn't called then sbi->sb will be equal to NULL. Code should check this ptr before dereferencing. Syzbot hit this issue via passing wrong mount param as can be seen from log below Fail log: ntfs3: Unknown parameter 'iochvrset' general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f] CPU: 1 PID: 3589 Comm: syz-executor210 Not tainted 5.18.0-rc3-syzkaller-00016-gb253435746d9 #0 ... Call Trace: <TASK> put_ntfs+0x1ed/0x2a0 fs/ntfs3/super.c:463 ntfs_fs_free+0x6a/0xe0 fs/ntfs3/super.c:1363 put_fs_context+0x119/0x7a0 fs/fs_context.c:469 do_new_mount+0x2b4/0xad0 fs/namespace.c:3044 do_mount fs/namespace.c:3383 [inline] __do_sys_mount fs/namespace.c:3591 [inline]

References

• https://git.kernel.org/stable/c/8e8e1a84dac7a3d2b432162a70d7fb6a75960772
• https://git.kernel.org/stable/c/bf6089dc01ba3194ab962105d7b85690843c256f
• https://git.kernel.org/stable/c/321460ca3b55f48b3ba6008248264ab2bd6407d9