{"id":"CVE-2026-68239","summary":"drm/ttm: Account for NULL and handle pages in ttm_pool_backup","details":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/ttm: Account for NULL and handle pages in ttm_pool_backup\n\nPages in ttm_pool_backup can be NULL or backup handles\n(ttm_backup_page_ptr_is_handle()), neither of which can be passed to\nset_pages_array_wb() or freed. Add a dedicated WB pass before the\ndma/purge loop that walks allocations using the same i += num_pages\nstride, skipping NULL and handle entries, and calls set_pages_array_wb()\nonce per contiguous run of real pages. Apply the same NULL/handle guard\nto the dma/purge loop.\n\nFixes the following oops:\n\nOops: general protection fault, kernel NULL pointer dereference 0x0: 0000 [#1] SMP NOPTI\nRIP: 0010:__cpa_process_fault+0xf8/0x770\nRSP: 0018:ffffc90000a87718 EFLAGS: 00010287\nRAX: 0000000000000000 RBX: ffffc90000a87868 RCX: 0000000000000000\nRDX: 0000000000001000 RSI: 0005088000000000 RDI: ffffffff827c5f34\nRBP: 0005088000000000 R08: ffffc90000a877cb R09: ffffc90000a877d0\nR10: 0000000000000000 R11: 000000000000001b R12: 000ffffffffff000\nR13: ffffc90000a87868 R14: ffffc90000a87868 R15: ffff88815b882ae0\nFS:  0000000000000000(0000) GS:ffff8884ec840000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 00007f930b844000 CR3: 000000000262e003 CR4: 0000000008f70ef0\nPKRU: 55555554\nCall Trace:\n \u003cTASK\u003e\n __change_page_attr_set_clr+0x989/0xe90\n ? __purge_vmap_area_lazy+0x6c/0x3a0\n ? _vm_unmap_aliases+0x250/0x2a0\n set_pages_array_wb+0x7f/0x120\n ttm_pool_backup+0x4c9/0x5b0 [ttm]\n ? dma_resv_wait_timeout+0x3b/0xf0\n ttm_tt_backup+0x32/0x60 [ttm]\n ttm_bo_shrink+0x66/0x110 [ttm]\n xe_bo_shrink_purge+0x12b/0x1b0 [xe]\n xe_bo_shrink+0xbb/0x270 [xe]\n __xe_shrinker_walk+0xf7/0x160 [xe]\n xe_shrinker_walk+0x9d/0xc0 [xe]\n xe_shrinker_scan+0x11f/0x210 [xe]\n do_shrink_slab+0x13b/0x270\n shrink_slab+0xf1/0x400\n shrink_node+0x352/0x8a0\n balance_pgdat+0x32c/0x700\n kswapd+0x205/0x2f0\n ? __pfx_autoremove_wake_function+0x10/0x10\n ? __pfx_kswapd+0x10/0x10\n kthread+0xd1/0x110\n ? __pfx_kthread+0x10/0x10\n ret_from_fork+0x1b1/0x200\n ? __pfx_kthread+0x10/0x10\n ret_from_fork_asm+0x1a/0x30\n \u003c/TASK\u003e","modified":"2026-08-18T03:31:14.153443442Z","published":"2026-08-10T12:01:04.297Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68239.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/22aa7fb4e7d0b3ab41d1240ed743167980912970"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5b7b3b6595ee77d01c7463757baed114786094dd"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9ddaabf38f7a45b329e34358b98d2968d8649d21"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68239.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-68239"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"b63d715b8090aed48bdef5930625946fa4c0d324"},{"fixed":"22aa7fb4e7d0b3ab41d1240ed743167980912970"},{"fixed":"9ddaabf38f7a45b329e34358b98d2968d8649d21"},{"fixed":"5b7b3b6595ee77d01c7463757baed114786094dd"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-68239.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.15.0"},{"fixed":"6.18.42"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-68239.json"}}],"schema_version":"1.9.0"}