CVE-2026-90001 is a vulnerability in Linux Kernel
Published on September 16, 2026
HID: bpf: serialize device reference release in struct_ops destroy path
In the Linux kernel, the following vulnerability has been resolved:
HID: bpf: serialize device reference release in struct_ops destroy path
__hid_bpf_ops_destroy_device() and hid_bpf_unreg() can race on the
same registration reference, double-putting struct hid_device and
freeing it while hid_destroy_device() still uses it. Serialize the
remove/NULL decision under hdev->bpf.prog_list_lock so exactly one
path releases each registration reference: unreg re-checks ops->hdev
under the lock and returns without putting when the destroy path
already cleared it; all put_device() calls happen after the lock is
dropped, which is safe because a concurrent unreg then observes
ops->hdev == NULL under the lock.
Background: each successful attach (hid_bpf_ops_reg) acquires one
device reference (hid_get_device()). Two paths can release it:
- device destruction: hid_destroy_device() -> hid_bpf_destroy_device()
-> __hid_bpf_ops_destroy_device(), which walks hdev->bpf.prog_list
under rcu_read_lock() and drops one reference per attached program;
- BPF link release: bpf map delete (no BPF_F_LINK) synchronously calls
st_ops->unreg() -> hid_bpf_unreg(), which drops the reference for
its own registration.
The coordination handshake (e->hdev = NULL on the destroy side vs
"if (!hdev) return" on the unreg side) is a TOCTOU check: the two
paths run under different lock domains (rcu_read_lock vs
prog_list_lock), so a concurrent unreg can read ops->hdev as
non-NULL, block on prog_list_lock, and then proceed while the
destroy traversal executes - both paths then drop the same
reference. The refcount reaches zero legitimately (each decrement
is individually valid), so no refcount_t saturation fires: the
device is simply freed while the transport is still inside
hid_destroy_device(), and subsequent teardown touches freed memory.
The fix serializes the remove/NULL decision under prog_list_lock on
both sides and moves the destroy-side puts outside the lock. With
the lock held, plain reads/writes of ops->hdev are sufficient; no
READ_ONCE/WRITE_ONCE are added, keeping the patch minimal.
Unlocked-read safety: the unlocked read of ops->hdev at the top of
hid_bpf_unreg() cannot touch a freed device, because the unreg path
itself still holds this registration's reference (released only by
its own hid_put_device() after the lock is dropped), and a destroy
traversal that already cleared ops->hdev makes the lock-internal
re-check return early without any put. At most one of the two
paths releases each registration reference.
Products Associated with CVE-2026-90001
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Affected Versions
Linux:- Version ebc0d8093e8c97de459615438edefad1a4ac352c and below 401359684620145be710de97b87e1a47abfe1459 is affected.
- Version ebc0d8093e8c97de459615438edefad1a4ac352c and below c7f927aa8b55008ed5ea0814313d5dad771dcf3c is affected.
- Version ebc0d8093e8c97de459615438edefad1a4ac352c and below bfb7939788f3c8dd080a4dd81e38d625b35d194e is affected.
- Version ebc0d8093e8c97de459615438edefad1a4ac352c and below 9cdc7e6dc7a99ad7311ad5e7c145f2b9ce4e24b0 is affected.
- Version 6.11 is affected.
- Before 6.11 is unaffected.
- Version 6.12.110, <= 6.12.* is unaffected.
- Version 6.18.51, <= 6.18.* is unaffected.
- Version 7.2.5, <= 7.2.* is unaffected.
- Version 7.3-rc2, <= * is unaffected.