{"id":"CVE-2026-90001","summary":"HID: bpf: serialize device reference release in struct_ops destroy path","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nHID: bpf: serialize device reference release in struct_ops destroy path\n\n__hid_bpf_ops_destroy_device() and hid_bpf_unreg() can race on the\nsame registration reference, double-putting struct hid_device and\nfreeing it while hid_destroy_device() still uses it.  Serialize the\nremove/NULL decision under hdev-\u003ebpf.prog_list_lock so exactly one\npath releases each registration reference: unreg re-checks ops-\u003ehdev\nunder the lock and returns without putting when the destroy path\nalready cleared it; all put_device() calls happen after the lock is\ndropped, which is safe because a concurrent unreg then observes\nops-\u003ehdev == NULL under the lock.\n\nBackground: each successful attach (hid_bpf_ops_reg) acquires one\ndevice reference (hid_get_device()).  Two paths can release it:\n\n- device destruction: hid_destroy_device() -\u003e hid_bpf_destroy_device()\n  -\u003e __hid_bpf_ops_destroy_device(), which walks hdev-\u003ebpf.prog_list\n  under rcu_read_lock() and drops one reference per attached program;\n- BPF link release: bpf map delete (no BPF_F_LINK) synchronously calls\n  st_ops-\u003eunreg() -\u003e hid_bpf_unreg(), which drops the reference for\n  its own registration.\n\nThe coordination handshake (e-\u003ehdev = NULL on the destroy side vs\n\"if (!hdev) return\" on the unreg side) is a TOCTOU check: the two\npaths run under different lock domains (rcu_read_lock vs\nprog_list_lock), so a concurrent unreg can read ops-\u003ehdev as\nnon-NULL, block on prog_list_lock, and then proceed while the\ndestroy traversal executes - both paths then drop the same\nreference.  The refcount reaches zero legitimately (each decrement\nis individually valid), so no refcount_t saturation fires: the\ndevice is simply freed while the transport is still inside\nhid_destroy_device(), and subsequent teardown touches freed memory.\n\nThe fix serializes the remove/NULL decision under prog_list_lock on\nboth sides and moves the destroy-side puts outside the lock.  With\nthe lock held, plain reads/writes of ops-\u003ehdev are sufficient; no\nREAD_ONCE/WRITE_ONCE are added, keeping the patch minimal.\n\nUnlocked-read safety: the unlocked read of ops-\u003ehdev at the top of\nhid_bpf_unreg() cannot touch a freed device, because the unreg path\nitself still holds this registration's reference (released only by\nits own hid_put_device() after the lock is dropped), and a destroy\ntraversal that already cleared ops-\u003ehdev makes the lock-internal\nre-check return early without any put.  At most one of the two\npaths releases each registration reference.","modified":"2026-09-18T03:48:34.621589145Z","published":"2026-09-16T10:33:12.063Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90001.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/401359684620145be710de97b87e1a47abfe1459"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9cdc7e6dc7a99ad7311ad5e7c145f2b9ce4e24b0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bfb7939788f3c8dd080a4dd81e38d625b35d194e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c7f927aa8b55008ed5ea0814313d5dad771dcf3c"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90001.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90001"},{"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":"ebc0d8093e8c97de459615438edefad1a4ac352c"},{"fixed":"401359684620145be710de97b87e1a47abfe1459"},{"fixed":"c7f927aa8b55008ed5ea0814313d5dad771dcf3c"},{"fixed":"bfb7939788f3c8dd080a4dd81e38d625b35d194e"},{"fixed":"9cdc7e6dc7a99ad7311ad5e7c145f2b9ce4e24b0"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90001.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.11.0"},{"fixed":"6.12.110"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.51"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90001.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}