CVE-2024-40962: In the Linux kernel, the following vulnerability has been resolved:  btrfs: zoned: allocate dummy checksums for zoned NODATASUM writes  Shin'ichiro reported that when he's running fstests' test-case btrfs/167 on emulated zoned devices, he's seeing the following NULL pointer dereference in 'btrfs_zone_finish_endio()':    Oops: general protection fault, probably for non-canonical address 0xdffffc0000000011: 0000 [#1] PREEMPT SMP KASAN NOPTI   KASAN: null-ptr-deref in range [0x0000000000000088-0x000000000000008f]   CPU: 4 PID: 2332440 Comm: kworker/u80:15 Tainted: G        W          6.10.0-rc2-kts+ #4   Hardware name: Supermicro Super Server/X11SPi-TF, BIOS 3.3 02/21/2020   Workqueue: btrfs-endio-write btrfs_work_helper [btrfs]   RIP: 0010:btrfs_zone_finish_endio.part.0+0x34/0x160 [btrfs]    RSP: 0018:ffff88867f107a90 EFLAGS: 00010206   RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff893e5534   RDX: 0000000000000011 RSI: 0000000000000004 RDI: 0000000000000088   RBP: 0000000000000002 R08: 0000000000000001 R09: ffffed1081696028   R10: ffff88840b4b0143 R11: ffff88834dfff600 R12: ffff88840b4b0000   R13: 0000000000020000 R14: 0000000000000000 R15: ffff888530ad5210   FS:  0000000000000000(0000) GS:ffff888e3f800000(0000) knlGS:0000000000000000   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033   CR2: 00007f87223fff38 CR3: 00000007a7c6a002 CR4: 00000000007706f0   DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000   DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400   PKRU: 55555554   Call Trace:    <TASK>    ? __die_body.cold+0x19/0x27    ? die_addr+0x46/0x70    ? exc_general_protection+0x14f/0x250    ? asm_exc_general_protection+0x26/0x30    ? do_raw_read_unlock+0x44/0x70    ? btrfs_zone_finish_endio.part.0+0x34/0x160 [btrfs]    btrfs_finish_one_ordered+0x5d9/0x19a0 [btrfs]    ? __pfx_lock_release+0x10/0x10    ? do_raw_write_lock+0x90/0x260    ? __pfx_do_raw_write_lock+0x10/0x10    ? __pfx_btrfs_finish_one_ordered+0x10/0x10 [btrfs]    ? _raw_write_unlock+0x23/0x40    ? btrfs_finish_ordered_zoned+0x5a9/0x850 [btrfs]    ? lock_acquire+0x435/0x500    btrfs_work_helper+0x1b1/0xa70 [btrfs]    ? __schedule+0x10a8/0x60b0    ? __pfx___might_resched+0x10/0x10    process_one_work+0x862/0x1410    ? __pfx_lock_acquire+0x10/0x10    ? __pfx_process_one_work+0x10/0x10    ? assign_work+0x16c/0x240    worker_thread+0x5e6/0x1010    ? __pfx_worker_thread+0x10/0x10    kthread+0x2c3/0x3a0    ? trace_irq_enable.constprop.0+0xce/0x110    ? __pfx_kthread+0x10/0x10    ret_from_fork+0x31/0x70    ? __pfx_kthread+0x10/0x10    ret_from_fork_asm+0x1a/0x30    </TASK>  Enabling CONFIG_BTRFS_ASSERT revealed the following assertion to trigger:    assertion failed: !list_empty(&ordered->list), in fs/btrfs/zoned.c:1815  This indicates, that we're missing the checksums list on the ordered_extent. As btrfs/167 is doing a NOCOW write this is to be expected.  Further analysis with drgn confirmed the assumption:    >>> inode = prog.crashed_thread().stack_trace()[11]['ordered'].inode   >>> btrfs_inode = drgn.container_of(inode, "struct btrfs_inode", \              "vfs_inode")   >>> print(btrfs_inode.flags)   (u32)1  As zoned emulation mode simulates conventional zones on regular devices, we cannot use zone-append for writing. But we're only attaching dummy checksums if we're doing a zone-append write.  So for NOCOW zoned data writes on conventional zones, also attach a dummy checksum.