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

ocfs2: fix NULL pointer dereference in ocfs2_journal_dirty()

bdev->bd_super has been removed and commit 8887b94d9322 change the usage
from bdev->bd_super to b_assoc_map->host->i_sb.  This introduces the
following NULL pointer dereference in ocfs2_journal_dirty() since
b_assoc_map is still not initialized.  This can be easily reproduced by
running xfstests generic/186, which simulate no more credits.

[  134.351592] BUG: kernel NULL pointer dereference, address: 0000000000000000
...
[  134.355341] RIP: 0010:ocfs2_journal_dirty+0x14f/0x160 [ocfs2]
...
[  134.365071] Call Trace:
[  134.365312]  <TASK>
[  134.365524]  ? __die_body+0x1e/0x60
[  134.365868]  ? page_fault_oops+0x13d/0x4f0
[  134.366265]  ? __pfx_bit_wait_io+0x10/0x10
[  134.366659]  ? schedule+0x27/0xb0
[  134.366981]  ? exc_page_fault+0x6a/0x140
[  134.367356]  ? asm_exc_page_fault+0x26/0x30
[  134.367762]  ? ocfs2_journal_dirty+0x14f/0x160 [ocfs2]
[  134.368305]  ? ocfs2_journal_dirty+0x13d/0x160 [ocfs2]
[  134.368837]  ocfs2_create_new_meta_bhs.isra.51+0x139/0x2e0 [ocfs2]
[  134.369454]  ocfs2_grow_tree+0x688/0x8a0 [ocfs2]
[  134.369927]  ocfs2_split_and_insert.isra.67+0x35c/0x4a0 [ocfs2]
[  134.370521]  ocfs2_split_extent+0x314/0x4d0 [ocfs2]
[  134.371019]  ocfs2_change_extent_flag+0x174/0x410 [ocfs2]
[  134.371566]  ocfs2_add_refcount_flag+0x3fa/0x630 [ocfs2]
[  134.372117]  ocfs2_reflink_remap_extent+0x21b/0x4c0 [ocfs2]
[  134.372994]  ? inode_update_timestamps+0x4a/0x120
[  134.373692]  ? __pfx_ocfs2_journal_access_di+0x10/0x10 [ocfs2]
[  134.374545]  ? __pfx_ocfs2_journal_access_di+0x10/0x10 [ocfs2]
[  134.375393]  ocfs2_reflink_remap_blocks+0xe4/0x4e0 [ocfs2]
[  134.376197]  ocfs2_remap_file_range+0x1de/0x390 [ocfs2]
[  134.376971]  ? security_file_permission+0x29/0x50
[  134.377644]  vfs_clone_file_range+0xfe/0x320
[  134.378268]  ioctl_file_clone+0x45/0xa0
[  134.378853]  do_vfs_ioctl+0x457/0x990
[  134.379422]  __x64_sys_ioctl+0x6e/0xd0
[  134.379987]  do_syscall_64+0x5d/0x170
[  134.380550]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
[  134.381231] RIP: 0033:0x7fa4926397cb
[  134.381786] Code: 73 01 c3 48 8b 0d bd 56 38 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 8d 56 38 00 f7 d8 64 89 01 48
[  134.383930] RSP: 002b:00007ffc2b39f7b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[  134.384854] RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007fa4926397cb
[  134.385734] RDX: 00007ffc2b39f7f0 RSI: 000000004020940d RDI: 0000000000000003
[  134.386606] RBP: 0000000000000000 R08: 00111a82a4f015bb R09: 00007fa494221000
[  134.387476] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
[  134.388342] R13: 0000000000f10000 R14: 0000558e844e2ac8 R15: 0000000000f10000
[  134.389207]  </TASK>

Fix it by only aborting transaction and journal in ocfs2_journal_dirty()
now, and leave ocfs2_abort() later when detecting an aborted handle,
e.g. start next transaction. Also log the handle details in this case.

kernel.org https://git.kernel.org/stable/c/0550ad87711f815b3d73e487ec58ca7d8f56edbc [No types assigned]

kernel.org https://git.kernel.org/stable/c/58f7e1e2c9e72c7974054c64c3abeac81c11f822 [No types assigned]

kernel.org https://git.kernel.org/stable/c/72663d3e09091f431a0774227ca207c0358362dd [No types assigned]