CVE-2022-50126: Reachable Assertion

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

jbd2: fix assertion 'jh->b_frozen_data == NULL' failure when journal aborted

Following process will fail assertion 'jh->b_frozen_data == NULL' in jbd2_journal_dirty_metadata():

jbd2_journal_commit_transaction unlink(dir/a) jh->b_transaction = trans1 jh->b_jlist = BJ_Metadata journal->j_running_transaction = NULL trans1->t_state = T_COMMIT unlink(dir/b) handle->h_trans = trans2 do_get_write_access jh->b_modified = 0 jh->b_frozen_data = frozen_buffer jh->b_next_transaction = trans2 jbd2_journal_dirty_metadata is_handle_aborted is_journal_aborted // return false

--> jbd2 abort <--

while (commit_transaction->t_buffers) if (is_journal_aborted) jbd2_journal_refile_buffer __jbd2_journal_refile_buffer WRITE_ONCE(jh->b_transaction, jh->b_next_transaction) WRITE_ONCE(jh->b_next_transaction, NULL) __jbd2_journal_file_buffer(jh, BJ_Reserved) J_ASSERT_JH(jh, jh->b_frozen_data == NULL) // assertion failure !

The reproducer (See detail in [Link]) reports: ------------[ cut here ]------------ kernel BUG at fs/jbd2/transaction.c:1629! invalid opcode: 0000 [#1] PREEMPT SMP CPU: 2 PID: 584 Comm: unlink Tainted: G W 5.19.0-rc6-00115-g4a57a8400075-dirty #697 RIP: 0010:jbd2_journal_dirty_metadata+0x3c5/0x470 RSP: 0018:ffffc90000be7ce0 EFLAGS: 00010202 Call Trace: <TASK> __ext4_handle_dirty_metadata+0xa0/0x290 ext4_handle_dirty_dirblock+0x10c/0x1d0 ext4_delete_entry+0x104/0x200 __ext4_unlink+0x22b/0x360 ext4_unlink+0x275/0x390 vfs_unlink+0x20b/0x4c0 do_unlinkat+0x42f/0x4c0 __x64_sys_unlink+0x37/0x50 do_syscall_64+0x35/0x80

After journal aborting, __jbd2_journal_refile_buffer() is executed with holding @jh->b_state_lock, we can fix it by moving 'is_handle_aborted()' into the area protected by @jh->b_state_lock.