Commit 64a6b36b0e18 for kernel

commit 64a6b36b0e1855288080bc5f89769f27d6dc03c8
Author: Chengfeng Ye <nicoyip.dev@gmail.com>
Date:   Thu Oct 8 16:44:44 2026 +0800

    net/smc: protect clcsock lifetime in smc_getname

    smc_getname() dereferences smc->clcsock without holding
    clcsock_release_lock. Link-group termination can release the CLC socket
    through smc_close_active_abort() while the SMC socket is still open,
    for example after shutdown(SHUT_WR).

    A getsockname() caller can load smc->clcsock, then the termination worker
    can clear the pointer and call sock_release() before the caller accesses
    clcsock->ops or invokes getname(). This causes a use-after-free; if the
    worker clears the pointer before the load, it causes a NULL dereference.
    The syscall's file reference keeps the SMC socket alive but does not
    prevent asynchronous release of its CLC socket.

    KASAN reported the following with test-only timing instrumentation:

      BUG: KASAN: slab-use-after-free in smc_getname+0x19e/0x1b0
      Read of size 8 at addr ffff888109abb4e0 by task poc/103
      Call Trace:
       smc_getname+0x19e/0x1b0
       do_getsockname+0xe5/0x170
       __sys_getsockname+0x8c/0x100

      Allocated by task 95:
       sock_alloc_inode+0x1e/0x280
       sock_alloc+0x3d/0x240
       __sock_create+0x7e/0x430
       smc_create+0x121/0x240

      Freed by task 0:
       kmem_cache_free+0xcc/0x340
       rcu_core+0x50a/0x1850

      Last potentially related work creation:
       evict+0x446/0x6c0
       smc_clcsock_release+0xa8/0xd0
       smc_close_active_abort+0x26a/0x3a0
       __smc_lgr_terminate.part.0+0x137/0x2e0

    Hold clcsock_release_lock across the pointer check and the getname()
    callback to serialize with smc_clcsock_release(). Return -EBADF if the
    CLC socket has already been released, preserving the existing peer
    state check and the callback's return value otherwise.

    Fixes: b03faa1fafc8 ("net/smc: postpone release of clcsock")
    Cc: stable@vger.kernel.org
    Signed-off-by: Chengfeng Ye <nicoyip.dev@gmail.com>
    Reviewed-by: Mahanta Jambigi <mjambigi@linux.ibm.com>
    Reviewed-by: Dust Li <dust.li@linux.alibaba.com>
    Link: https://patch.msgid.link/20261008084444.787449-1-nicoyip.dev@gmail.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index e9f93b3ab435..8b3ee70f8433 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -2784,6 +2784,7 @@ int smc_getname(struct socket *sock, struct sockaddr *addr,
 		int peer)
 {
 	struct smc_sock *smc;
+	int rc = -EBADF;

 	if (peer && (sock->sk->sk_state != SMC_ACTIVE) &&
 	    (sock->sk->sk_state != SMC_APPCLOSEWAIT1))
@@ -2791,7 +2792,11 @@ int smc_getname(struct socket *sock, struct sockaddr *addr,

 	smc = smc_sk(sock->sk);

-	return smc->clcsock->ops->getname(smc->clcsock, addr, peer);
+	mutex_lock(&smc->clcsock_release_lock);
+	if (smc->clcsock)
+		rc = smc->clcsock->ops->getname(smc->clcsock, addr, peer);
+	mutex_unlock(&smc->clcsock_release_lock);
+	return rc;
 }

 int smc_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)