fs/ntfs3: Fix NULL pointer dereference in 'ni_write_inode'

In the Linux kernel, the following vulnerability has been resolved:

fs/ntfs3: Fix NULL pointer dereference in 'ni_write_inode'

Syzbot found the following issue:

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000016

Mem abort info:

ESR = 0x0000000096000006

EC = 0x25: DABT (current EL), IL = 32 bits

SET = 0, FnV = 0

EA = 0, S1PTW = 0

FSC = 0x06: level 2 translation fault

Data abort info:

ISV = 0, ISS = 0x00000006

CM = 0, WnR = 0

user pgtable: 4k pages, 48-bit VAs, pgdp=000000010af56000

[0000000000000016] pgd=08000001090da003, p4d=08000001090da003, pud=08000001090ce003, pmd=0000000000000000

Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP

Modules linked in:

CPU: 1 PID: 3036 Comm: syz-executor206 Not tainted 6.0.0-rc6-syzkaller-17739-g16c9f284e746 #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022

pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)

pc : is_rec_inuse fs/ntfs3/ntfs.h:313 [inline]

pc : ni_write_inode+0xac/0x798 fs/ntfs3/frecord.c:3232

lr : ni_write_inode+0xa0/0x798 fs/ntfs3/frecord.c:3226

sp : ffff8000126c3800

x29: ffff8000126c3860 x28: 0000000000000000 x27: ffff0000c8b02000

x26: ffff0000c7502320 x25: ffff0000c7502288 x24: 0000000000000000

x23: ffff80000cbec91c x22: ffff0000c8b03000 x21: ffff0000c8b02000

x20: 0000000000000001 x19: ffff0000c75024d8 x18: 00000000000000c0

x17: ffff80000dd1b198 x16: ffff80000db59158 x15: ffff0000c4b6b500

x14: 00000000000000b8 x13: 0000000000000000 x12: ffff0000c4b6b500

x11: ff80800008be1b60 x10: 0000000000000000 x9 : ffff0000c4b6b500

x8 : 0000000000000000 x7 : ffff800008be1b50 x6 : 0000000000000000

x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000

x2 : 0000000000000008 x1 : 0000000000000001 x0 : 0000000000000000

Call trace:

is_rec_inuse fs/ntfs3/ntfs.h:313 [inline]

ni_write_inode+0xac/0x798 fs/ntfs3/frecord.c:3232

ntfs_evict_inode+0x54/0x84 fs/ntfs3/inode.c:1744

evict+0xec/0x334 fs/inode.c:665

iput_final fs/inode.c:1748 [inline]

iput+0x2c4/0x324 fs/inode.c:1774

ntfs_new_inode+0x7c/0xe0 fs/ntfs3/fsntfs.c:1660

ntfs_create_inode+0x20c/0xe78 fs/ntfs3/inode.c:1278

ntfs_create+0x54/0x74 fs/ntfs3/namei.c:100

lookup_open fs/namei.c:3413 [inline]

open_last_lookups fs/namei.c:3481 [inline]

path_openat+0x804/0x11c4 fs/namei.c:3688

do_filp_open+0xdc/0x1b8 fs/namei.c:3718

do_sys_openat2+0xb8/0x22c fs/open.c:1311

do_sys_open fs/open.c:1327 [inline]

__do_sys_openat fs/open.c:1343 [inline]

__se_sys_openat fs/open.c:1338 [inline]

__arm64_sys_openat+0xb0/0xe0 fs/open.c:1338

__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]

invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]

el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142

do_el0_svc+0x48/0x164 arch/arm64/kernel/syscall.c:206

el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:636

el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:654

el0t_64_sync+0x18c/0x190

Code: 97dafee4 340001b4 f9401328 2a1f03e0 (79402d14)

---[ end trace 0000000000000000 ]---

Above issue may happens as follows:

ntfs_new_inode

mi_init

mi->mrec = kmalloc(sbi->record_size, GFP_NOFS); -->failed to allocate memory

if (!mi->mrec)

return -ENOMEM;

iput

iput_final

evict

ntfs_evict_inode

ni_write_inode

is_rec_inuse(ni->mi.mrec)-> As 'ni->mi.mrec' is NULL trigger NULL-ptr-deref

To solve above issue if new inode failed make inode bad before call 'iput()' in

'ntfs_new_inode()'.