CVE-2026-90385

In the Linux kernel, the following vulnerability has been resolved:

md/raid1: create serial pool adding rdev to array with serialize_policy=1

The following bug has been observed with kernel 7.1.3 after adding a new rdev to an existing RAID1 array with serialize_policy enabled:

Oops: 0002 [#1] CPU: 0 UID: 0 PID: 19639 Comm: ext4lazyinit Not tainted 7.1.3-1-default RIP: _raw_spin_lock_irqsave+0x27/0x50 CR2: 0000000000004960 Call Trace: wait_for_serialization+0xb9/0x260 [raid1] raid1_make_request+0x762/0xaff [raid1] md_handle_request+0x1c9/0x2e0 [md_mod]

The raid1.c code calls wait_for_serialization() if the MD_SERIALIZE_POLICY is set, and wait_for_serialization assumes that rdev->serial is initialized. Normally this will be the case for arrays that have the serialize_policy sysfs attribute set to 1.

But when a new rdev is added to an existing array in bind_rdev_to_array(), the condition at mddev_create_serial_pool() causes creation of rdev->serial to be skipped. Fix it.