Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: SUNRPC: pin upper rpc_clnt across the TLS connect_worker The TLS connect path has a use-after-free: nothing pins the upper rpc_clnt across the delayed connect_worker. xs_connect() stores task->tk_client in sock_xprt::clnt as a raw pointer and queues the worker; for TLS-secured transports that worker is xs_tcp_tls_setup_socket(), which reads several fields out of the saved pointer (cl_timeout, cl_program, cl_prog, cl_vers, cl_cred, cl_stats) to construct the args for the inner handshake rpc_clnt. The xprt does not reference the rpc_clnt; the rpc_clnt references the xprt. xs_destroy() does cancel the connect_worker, but it runs only when the xprt's refcount drops to zero, which cannot happen until the rpc_clnt releases its cl_xprt reference in rpc_free_client_work(). When a TLS handshake fails fatally (for example, an mTLS mount whose client cert does not match the server), the connecting task is woken with -EACCES and exits, the mount caller invokes rpc_shutdown_client(), and the upper rpc_clnt is freed before the queued connect_worker fires. xs_tcp_tls_setup_socket() then dereferences the freed clnt, producing the refcount_t underflow Michael Nemanov reported. Take a reference on the upper rpc_clnt in xs_connect() for TLS transports via a new rpc_hold_client() helper, and drop it in the connect_worker's exit path with rpc_release_client(). The xprt_lock_connect() / xprt_unlock_connect() pairing already serialises xs_connect() with xs_tcp_tls_setup_socket(), so the take and release are balanced one-for-one. The non-TLS connect worker (xs_tcp_setup_socket) never reads sock_xprt::clnt, so leave that path alone and avoid the clnt-holds-xprt-holds-clnt cycle that would otherwise prevent xprt destruction.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 75eb6af7acdf566c68d61e98e67ee2f235201c02 before 79cd550f8c884523b604fbfa43eb02def74d6224; affected 75eb6af7acdf566c68d61e98e67ee2f235201c02 before 7a65b41b657b71d5a77861f47dd13eb4bc8e10d0; affected 75eb6af7acdf566c68d61e98e67ee2f235201c02 before 5b0427ba582d143a364301f825f4e32272f06d2d; affected 75eb6af7acdf566c68d61e98e67ee2f235201c02 before d49f6d098ed48775b9d27a9f9c5c220fdf76f102; affected 75eb6af7acdf566c68d61e98e67ee2f235201c02 before 46bc86c833956219bbfd246c1ffd832a479c5199 |
| Linux / Linux | affected 6.5; unaffected 0 before 6.5; unaffected 6.6.145 through 6.6.*; unaffected 6.12.97 through 6.12.*; unaffected 6.18.40 through 6.18.*; unaffected 7.1.5 through 7.1.*; unaffected 7.2 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/79cd550f8c884523b604fbfa43eb02def74d6224
- https://git.kernel.org/stable/c/7a65b41b657b71d5a77861f47dd13eb4bc8e10d0
- https://git.kernel.org/stable/c/5b0427ba582d143a364301f825f4e32272f06d2d
- https://git.kernel.org/stable/c/d49f6d098ed48775b9d27a9f9c5c220fdf76f102
- https://git.kernel.org/stable/c/46bc86c833956219bbfd246c1ffd832a479c5199
ADP enrichment
No English description supplied.
No references supplied.