CVE-2024-43874 crypto: ccp - Fix null pointer dereference in __sev_snp_shutdown_locked
In the Linux kernel, the following vulnerability has been resolved:

crypto: ccp - Fix null pointer dereference in __sev_snp_shutdown_locked

Fix a null pointer dereference induced by DEBUG_TEST_DRIVER_REMOVE.
Return from __sev_snp_shutdown_locked() if the psp_device or the
sev_device structs are not initialized. Without the fix, the driver will
produce the following splat:

   ccp 0000:55:00.5: enabling device (0000 -> 0002)
   ccp 0000:55:00.5: sev enabled
   ccp 0000:55:00.5: psp enabled
   BUG: kernel NULL pointer dereference, address: 00000000000000f0
   #PF: supervisor read access in kernel mode
   #PF: error_code(0x0000) - not-present page
   PGD 0 P4D 0
   Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
   CPU: 262 PID: 1 Comm: swapper/0 Not tainted 6.9.0-rc1+ #29
   RIP: 0010:__sev_snp_shutdown_locked+0x2e/0x150
   Code: 00 55 48 89 e5 41 57 41 56 41 54 53 48 83 ec 10 41 89 f7 49 89 fe 65 48 8b 04 25 28 00 00 00 48 89 45 d8 48 8b 05 6a 5a 7f 06 <4c> 8b a0 f0 00 00 00 41 0f b6 9c 24 a2 00 00 00 48 83 fb 02 0f 83
   RSP: 0018:ffffb2ea4014b7b8 EFLAGS: 00010286
   RAX: 0000000000000000 RBX: ffff9e4acd2e0a28 RCX: 0000000000000000
   RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffb2ea4014b808
   RBP: ffffb2ea4014b7e8 R08: 0000000000000106 R09: 000000000003d9c0
   R10: 0000000000000001 R11: ffffffffa39ff070 R12: ffff9e49d40590c8
   R13: 0000000000000000 R14: ffffb2ea4014b808 R15: 0000000000000000
   FS:  0000000000000000(0000) GS:ffff9e58b1e00000(0000) knlGS:0000000000000000
   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
   CR2: 00000000000000f0 CR3: 0000000418a3e001 CR4: 0000000000770ef0
   PKRU: 55555554
   Call Trace:
    <TASK>
    ? __die_body+0x6f/0xb0
    ? __die+0xcc/0xf0
    ? page_fault_oops+0x330/0x3a0
    ? save_trace+0x2a5/0x360
    ? do_user_addr_fault+0x583/0x630
    ? exc_page_fault+0x81/0x120
    ? asm_exc_page_fault+0x2b/0x30
    ? __sev_snp_shutdown_locked+0x2e/0x150
    __sev_firmware_shutdown+0x349/0x5b0
    ? pm_runtime_barrier+0x66/0xe0
    sev_dev_destroy+0x34/0xb0
    psp_dev_destroy+0x27/0x60
    sp_destroy+0x39/0x90
    sp_pci_remove+0x22/0x60
    pci_device_remove+0x4e/0x110
    really_probe+0x271/0x4e0
    __driver_probe_device+0x8f/0x160
    driver_probe_device+0x24/0x120
    __driver_attach+0xc7/0x280
    ? driver_attach+0x30/0x30
    bus_for_each_dev+0x10d/0x130
    driver_attach+0x22/0x30
    bus_add_driver+0x171/0x2b0
    ? unaccepted_memory_init_kdump+0x20/0x20
    driver_register+0x67/0x100
    __pci_register_driver+0x83/0x90
    sp_pci_init+0x22/0x30
    sp_mod_init+0x13/0x30
    do_one_initcall+0xb8/0x290
    ? sched_clock_noinstr+0xd/0x10
    ? local_clock_noinstr+0x3e/0x100
    ? stack_depot_save_flags+0x21e/0x6a0
    ? local_clock+0x1c/0x60
    ? stack_depot_save_flags+0x21e/0x6a0
    ? sched_clock_noinstr+0xd/0x10
    ? local_clock_noinstr+0x3e/0x100
    ? __lock_acquire+0xd90/0xe30
    ? sched_clock_noinstr+0xd/0x10
    ? local_clock_noinstr+0x3e/0x100
    ? __create_object+0x66/0x100
    ? local_clock+0x1c/0x60
    ? __create_object+0x66/0x100
    ? parameq+0x1b/0x90
    ? parse_one+0x6d/0x1d0
    ? parse_args+0xd7/0x1f0
    ? do_initcall_level+0x180/0x180
    do_initcall_level+0xb0/0x180
    do_initcalls+0x60/0xa0
    ? kernel_init+0x1f/0x1d0
    do_basic_setup+0x41/0x50
    kernel_init_freeable+0x1ac/0x230
    ? rest_init+0x1f0/0x1f0
    kernel_init+0x1f/0x1d0
    ? rest_init+0x1f0/0x1f0
    ret_from_fork+0x3d/0x50
    ? rest_init+0x1f0/0x1f0
    ret_from_fork_asm+0x11/0x20
    </TASK>
   Modules linked in:
   CR2: 00000000000000f0
   ---[ end trace 0000000000000000 ]---
   RIP: 0010:__sev_snp_shutdown_locked+0x2e/0x150
   Code: 00 55 48 89 e5 41 57 41 56 41 54 53 48 83 ec 10 41 89 f7 49 89 fe 65 48 8b 04 25 28 00 00 00 48 89 45 d8 48 8b 05 6a 5a 7f 06 <4c> 8b a0 f0 00 00 00 41 0f b6 9c 24 a2 00 00 00 48 83 fb 02 0f 83
   RSP: 0018:ffffb2ea4014b7b8 EFLAGS: 00010286
   RAX: 0000000000000000 RBX: ffff9e4acd2e0a28 RCX: 0000000000000000
   RDX: 0000000
---truncated---
CVSS v3.1 score: 5.5