A null dereference crash occurs in ttm_tt_unpopulate() where Symantec SEP modules are installed and loaded.

Issue

• A null dereference crash occurs in ttm_tt_unpopulate() where Symantec SEP modules are installed and loaded.
• The system was running out of memory at the time of the crash.

[435472.543288] Out of memory: Killed process 2011 (gnome-shell) total-vm:3081520kB, anon-rss:96804kB, file-rss:26616kB, shmem-rss:12kB, UID:42
[435472.613862] BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
[435472.613900] PGD 0 P4D 0 
[435472.613914] Oops: 0002 [#1] SMP PTI
[435472.613930] CPU: 0 PID: 1 Comm: systemd Kdump: loaded Tainted: P           OE    --------- -  - 4.18.0-193.19.1.el8_2.x86_64 #1
[435472.613973] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 12/12/2018
[435472.614017] RIP: 0010:ttm_tt_unpopulate+0x22/0x60 [ttm]
[435472.614039] Code: 0f 1f 84 00 00 00 00 00 66 66 66 66 90 83 7f 3c 02 74 4a f6 47 19 01 75 2f 48 83 7f 20 00 74 28 48 8b 57 10 31 c0 48 8b 0c c2 <48> c7 41 18 00 00 00 00 48 8b 0c c2 48 83 c0 01 48 c7 41 20 00 00
[435472.614104] RSP: 0018:ffffa6bf80033d40 EFLAGS: 00010287
[435472.614124] RAX: 0000000000000001 RBX: ffff8fe5ec781700 RCX: 0000000000000000
[435472.614151] RDX: ffff8fe5e8d36000 RSI: ffff8fe5dddbf054 RDI: ffff8fe5ec781700
[435472.614177] RBP: ffff8fe6782e6000 R08: ffff8fe67082fb18 R09: ffff8fe647c0f000
[435472.614203] R10: ffff8fe6708a0900 R11: 0000000000000008 R12: ffffffffc050f2f0
[435472.614229] R13: ffff8fe5dddbf8ac R14: ffff8fe5dddbfa48 R15: dead000000000100
[435472.614256] FS:  00007fcb45685680(0000) GS:ffff8fe679c00000(0000) knlGS:0000000000000000
[435472.614286] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[435472.614307] CR2: 0000000000000018 CR3: 0000000138916003 CR4: 00000000000606f0
[435472.614369] Call Trace:
[435472.615143]  ttm_tt_destroy.part.11+0x49/0x50 [ttm]
[435472.615892]  ttm_bo_cleanup_memtype_use+0x2e/0x70 [ttm]
[435472.616669]  ttm_bo_release+0x265/0x2d0 [ttm]
[435472.617408]  ttm_prime_refcount_release+0x3f/0x60 [vmwgfx]
[435472.618151]  ttm_release_base+0x88/0xb0 [vmwgfx]
[435472.618903]  ttm_ref_object_release+0xb8/0xe0 [vmwgfx]
[435472.619654]  ttm_object_file_release+0x39/0x90 [vmwgfx]
[435472.620441]  vmw_postclose+0x3a/0x50 [vmwgfx]
[435472.621215]  drm_file_free.part.10+0x1dc/0x290 [drm]
[435472.622003]  drm_release+0xa9/0xe0 [drm]
[435472.622766]  __fput+0xb7/0x230
[435472.623527]  task_work_run+0x8a/0xb0
[435472.624295]  exit_to_usermode_loop+0xeb/0xf0
[435472.625073]  do_syscall_64+0x198/0x1a0
[435472.625858]  entry_SYSCALL_64_after_hwframe+0x65/0xca
[435472.626607] RIP: 0033:0x7fcb43ca4c27
[435472.627370] Code: 12 b8 03 00 00 00 0f 05 48 3d 00 f0 ff ff 77 3b c3 66 90 53 89 fb 48 83 ec 10 e8 c4 fb ff ff 89 df 89 c2 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 2b 89 d7 89 44 24 0c e8 06 fc ff ff 8b 44 24
[435472.629078] RSP: 002b:00007fff0e149f20 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
[435472.629947] RAX: 0000000000000000 RBX: 0000000000000063 RCX: 00007fcb43ca4c27
[435472.630876] RDX: 0000000000000000 RSI: 0000000000000007 RDI: 0000000000000063
[435472.631815] RBP: 00007fcb45685450 R08: 000055614d52f010 R09: 0000000000000006
[435472.632645] R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
[435472.633484] R13: 0000000000000000 R14: 0000000000000000 R15: 000055614ce3b458
[435472.634319] Modules linked in: tcp_diag udp_diag inet_diag nf_tables nfnetlink binfmt_misc symap_custom_4_18_0_193_19_1_el8_2_x86_64(POE) symev_custom_4_18_0_193_19_1_el8_2_x86_64(OE) vmw_vsock_vmci_transport vsock intel_rapl_msr intel_rapl_common sb_edac crct10dif_pclmul crc32_pclmul ghash_clmulni_intel vmw_balloon intel_rapl_perf joydev pcspkr i2c_piix4 vmw_vmci auth_rpcgss sunrpc ip_tables ext4 mbcache jbd2 sr_mod cdrom ata_generic sd_mod sg vmwgfx crc32c_intel drm_kms_helper ata_piix syscopyarea sysfillrect sysimgblt fb_sys_fops serio_raw ttm libata drm vmxnet3 vmw_pvscsi dm_mirror dm_region_hash dm_log dm_mod fuse
[435472.638201] CR2: 0000000000000018