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.