CVE-2026-72381

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

ksmbd: fix use-after-free of fp->owner.name in durable handle owner check

Two concurrent SMB2 durable reconnects (DH2C/DHnC) on the same

persistent_id race the fp->owner.name compare-read in

ksmbdvfscomparedurableowner() against the kfree() in

ksmbdreopendurable_fd()'s reopen-success path. fp->owner.name is a

standalone kstrdup() buffer whose lifetime is independent of the fp

refcount, and the two sites share no lock: the compare reads the buffer

while the reopen frees it, so the strcmp() can dereference freed memory.

Commit 7ce4fc40018d ("ksmbd: fix durable reconnect double-bind race in

ksmbdreopendurable_fd") made the fp->conn claim atomic under

globalft.lock (closing the owner.name double-free and the ksmbdfile

write-UAF), but the compare-read versus reopen-free pair was left

unserialized.

  BUG: KASAN: slab-use-after-free in strcmp+0x2c/0x80

  Read of size 1 by task kworker

    strcmp

    ksmbdvfscomparedurableowner

    smb2checkdurable_oplock

    smb2_open

  Freed by task kworker:

    kfree

    ksmbdreopendurable_fd

    smb2_open

  Allocated by task kworker:

    kstrdup

    sessionfdcheck

    smb2sessionlogoff

  The buggy address belongs to the cache kmalloc-8

Serialize both sides of the race with fp->f_lock.  The global durable

file-table lock still protects the durable reconnect claim, but

fp->owner.name is per-open state and does not need to block unrelated

durable table lookups or reconnects.  The teardown is left at its

existing location after the reopen-success point so that an _openid()

rollback still retains owner.name for a later legitimate reconnect to

verify.