CVE-2025-68263

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

ksmbd: ipc: fix use-after-free in ipc_msg_send_request

ipc_msg_send_request() waits for a generic netlink reply using an

ipc_msg_table_entry on the stack. The generic netlink handler

(handle_generic_event()/handle_response()) fills entry->response under

ipc_msg_table_lock, but ipc_msg_send_request() used to validate and free

entry->response without holding the same lock.

Under high concurrency this allows a race where handle_response() is

copying data into entry->response while ipc_msg_send_request() has just

freed it, leading to a slab-use-after-free reported by KASAN in

handle_generic_event():

BUG: KASAN: slab-use-after-free in handle_generic_event+0x3c4/0x5f0 [ksmbd]

Write of size 12 at addr ffff888198ee6e20 by task pool/109349

...

Freed by task:

kvfree

ipc_msg_send_request [ksmbd]

ksmbd_rpc_open -> ksmbd_session_rpc_open [ksmbd]

Fix by:

- Taking ipc_msg_table_lock in ipc_msg_send_request() while validating

entry->response, freeing it when invalid, and removing the entry from

ipc_msg_table.

- Returning the final entry->response pointer to the caller only after

the hash entry is removed under the lock.

- Returning NULL in the error path, preserving the original API

semantics.

This makes all accesses to entry->response consistent with

handle_response(), which already updates and fills the response buffer

under ipc_msg_table_lock, and closes the race that allowed the UAF.