ACK: [SRU][J][PATCH 0/1] CVE-2025-37926

[Edoardo Canepa]

Acked-by: Edoardo Canepa <edoardo.canepa at canonical.com>

On 9/10/26 05:18, Cengiz Can via kernel-team wrote:
> https://ubuntu.com/security/CVE-2025-37926
>
> [ Impact ]
>
> In the Linux kernel, the following vulnerability has been resolved:
>
> ksmbd: fix use-after-free in ksmbd_session_rpc_open
>
> A UAF issue can occur due to a race condition between ksmbd_session_rpc_open()
> and __session_rpc_close(). Add rpc_lock to the session to protect it.
>
> [ Fix ]
>
> jammy/linux: backported from a1f46c99d9ea
>
> The fix adds a per-session rpc_lock (an rwsem) that serialises access to the
> session RPC list, closing the race window between ksmbd_session_rpc_open() and
> __session_rpc_close() that could otherwise lead to a use-after-free.
>
> The backport keeps this tree's atomic_set(refcnt, 1) and initialises the new
> rwsem; the unrelated refcnt drift from the upstream commit is not carried over.
> GFP_KERNEL is used in place of the not-yet-defined KSMBD_DEFAULT_GFP, and the
> affected file lives at fs/ksmbd/ rather than fs/smb/server/ in this tree.
>
> [ Test Plan ]
>
> Build and boot tested.
>
> [ Where Problems Could Occur ]
>
> A bad fix would affect systems that run the in-kernel ksmbd SMB server and
> serve files to SMB clients, where the added locking could in principle change
> RPC handling behaviour or, if wrong, introduce a deadlock under concurrent
> session setup and teardown. Systems that do not load or use the ksmbd module,
> including those that rely on user-space Samba instead, are not affected.
>
> [ Other Info ]
>
> Kybele flow-v11-25-ga27c0fa6. Reference: cc51ef1e/v1
>
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