Wind River Support Network

Description

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.