CVE-2026-64141

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

ksmbd: fix null pointer dereference in compare_guid_key()

session_fd_check() walks the per-inode m_op_list during durable-handle

session teardown and sets op->conn = NULL for every opinfo whose conn

matched the closing session's connection. The matching opinfo, however,

stays linked in its per-ClientGuid lease_table_list entry's lb->lease_list

because destroy_lease_table() only runs on full TCP-connection teardown,

not on SESSION_LOGOFF.

If the same TCP connection then negotiates a fresh session with the

same ClientGuid (ClientGuid is bound to NEGOTIATE, not the session, and

is unchanged across LOGOFF + SETUP) and issues a SMB2 CREATE with a

lease context on a different inode, find_same_lease_key() walks

lb->lease_list, reaches the stale opinfo, and calls compare_guid_key(),

which unconditionally dereferences opinfo->conn->ClientGUID. The conn

pointer is NULL and the kernel panics.

Reproducer requires only a successful SMB2 SESSION_SETUP and a share

configured with 'durable handles = yes'. KASAN report on mainline

70390501d194:

general protection fault, probably for non-canonical address

0xdffffc0000000069: 0000 [#1] SMP KASAN PTI

KASAN: null-ptr-deref in range [0x0000000000000348-0x000000000000034f]

Workqueue: ksmbd-io handle_ksmbd_work

RIP: 0010:bcmp+0x5b/0x230

Call Trace:

compare_guid_key+0x4b/0xd0

find_same_lease_key+0x324/0x690

smb2_open+0x6aea/0x8e60

handle_ksmbd_work+0x796/0xee0

...

Faulting address 0x348 is the offset of ClientGUID within struct

ksmbd_conn, confirming opinfo->conn was NULL.

Read opinfo->conn once and bail out if it has been cleared by a

concurrent session_fd_check(). A half-detached opinfo cannot be the

owner of an active lease, so returning 0 is the correct match result.