CVE-2025-68263

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

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

ipcmsgsendrequest() waits for a generic netlink reply using an ipcmsgtableentry on the stack. The generic netlink handler (handlegenericevent()/handleresponse()) fills entry->response under ipcmsgtablelock, but ipcmsgsend_request() used to validate and free entry->response without holding the same lock.

Under high concurrency this allows a race where handleresponse() is copying data into entry->response while ipcmsgsendrequest() has just freed it, leading to a slab-use-after-free reported by KASAN in handlegenericevent():

BUG: KASAN: slab-use-after-free in handlegenericevent+0x3c4/0x5f0 [ksmbd] Write of size 12 at addr ffff888198ee6e20 by task pool/109349 ... Freed by task: kvfree ipcmsgsendrequest [ksmbd] ksmbdrpcopen -> ksmbdsessionrpcopen [ksmbd]

Fix by: - Taking ipcmsgtablelock in ipcmsgsendrequest() while validating entry->response, freeing it when invalid, and removing the entry from ipcmsgtable. - 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 handleresponse(), which already updates and fills the response buffer under ipcmsgtablelock, and closes the race that allowed the UAF.