{"id":"CVE-2026-89809","summary":"drm/amdkfd: fix scope of mqd_mgr dereference in pqm_debugfs_mqds","details":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/amdkfd: fix scope of mqd_mgr dereference in pqm_debugfs_mqds\n\nReading /sys/kernel/debug/kfd/mqds while a process holds an active KFD\nqueue triggers a NULL pointer dereference because the for loop that\ncalls mqd_mgr-\u003edebugfs_show_mqd() is incorrectly placed outside the\nif (pqn-\u003eq) block that initializes mqd_mgr.\n\nThe queue list can contain entries where pqn-\u003eq is NULL (kernel queues\nwhere only pqn-\u003ekq is valid). In the original code:\n\n  if (pqn-\u003eq) {\n      ...\n      mqd_mgr = q-\u003edevice-\u003edqm-\u003emqd_mgrs[mqd_type];\n      size = mqd_mgr-\u003emqd_stride(...);\n  }\n\n  for (xcc = 0; xcc \u003c num_xccs; xcc++) {  // WRONG: outside if block\n      mqd = q-\u003emqd + size * xcc;\n      r = mqd_mgr-\u003edebugfs_show_mqd(m, mqd);\n  }\n\nWhen iterating over a queue node where pqn-\u003eq is NULL:\n1. The if (pqn-\u003eq) block is skipped\n2. mqd_mgr remains uninitialized (NULL from declaration)\n3. The for loop executes anyway\n4. mqd_mgr-\u003edebugfs_show_mqd(m, mqd) dereferences NULL\n\nThe crash manifests as:\n\n  BUG: kernel NULL pointer dereference, address: 0000000000000000\n  #PF: supervisor instruction fetch in kernel mode\n  RIP: 0010:0x0\n  Call Trace:\n   pqm_debugfs_mqds+0x10c/0x1d0 [amdgpu]\n   kfd_debugfs_mqds_by_process+0x9b/0x110 [amdgpu]\n   seq_read_iter+0x132/0x4b0\n   ...\n\nFix by moving the for loop inside the if (pqn-\u003eq) block, so mqd_mgr\nand related variables are only used when properly initialized.\n\n(cherry picked from commit 8bfe29d5c798940f797aa24135d2734c3ffce9de)","modified":"2026-09-25T18:27:28.438957973Z","published":"2026-09-16T10:30:42.445Z","related":["openSUSE-SU-2026:11880-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89809.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/012a026bae0212952b423a842b7e2c0bf21f8e7a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/58e866711b234571b0ce342c43d153a4786b32b8"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89809.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89809"},{"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":"e1b73b64271d706079370b58b81292dafd373163"},{"fixed":"58e866711b234571b0ce342c43d153a4786b32b8"},{"fixed":"012a026bae0212952b423a842b7e2c0bf21f8e7a"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-89809.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"7.0.0"},{"fixed":"7.2.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-89809.json"}}],"schema_version":"1.9.0"}