Commit 937d61f86d37 for kernel

commit 937d61f86d377a3aa578adae7a3dfcecdddf9d89
Author: Shuangpeng Bai <shuangpeng.kernel@gmail.com>
Date:   Mon Jun 29 13:14:22 2026 -0400

    libceph: refresh auth->authorizer_buf{,_len} after authorizer update

    ceph_x_create_authorizer() caches au->buf->vec.iov_base and
    au->buf->vec.iov_len in struct ceph_auth_handshake.  These
    cached values are then used by the messenger connect code when
    sending the authorizer.

    ceph_x_update_authorizer() can rebuild the authorizer when a newer
    service ticket is available.  If the rebuilt authorizer no longer
    fits in the existing buffer, ceph_x_build_authorizer() drops its
    reference to au->buf and allocates a new one.  If this is the final
    reference, ceph_buffer_put() frees the old ceph_buffer and its
    vec.iov_base, but auth->authorizer_buf still points at that freed
    memory.

    A subsequent msgr1 reconnect can therefore queue the stale pointer
    and trigger a KASAN slab-use-after-free in _copy_from_iter() while
    tcp_sendmsg() copies the authorizer.

    Refresh auth->authorizer_buf and auth->authorizer_buf_len after a
    successful authorizer rebuild so the messenger sends the current
    buffer.

    Cc: stable@vger.kernel.org
    Fixes: 0bed9b5c523d ("libceph: add update_authorizer auth method")
    Closes: https://lore.kernel.org/all/E378850E-106C-427B-A241-970EB2D054D7@gmail.com/
    Signed-off-by: Shuangpeng Bai <shuangpeng.kernel@gmail.com>
    Reviewed-by: Alex Markuze <amarkuze@redhat.com>
    Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

diff --git a/net/ceph/auth_x.c b/net/ceph/auth_x.c
index 9e64e82d0b63..50a79e8aa656 100644
--- a/net/ceph/auth_x.c
+++ b/net/ceph/auth_x.c
@@ -849,9 +849,16 @@ static int ceph_x_update_authorizer(

 	au = (struct ceph_x_authorizer *)auth->authorizer;
 	if (au->secret_id < th->secret_id) {
+		int ret;
+
 		dout("ceph_x_update_authorizer service %u secret %llu < %llu\n",
 		     au->service, au->secret_id, th->secret_id);
-		return ceph_x_build_authorizer(ac, th, au);
+		ret = ceph_x_build_authorizer(ac, th, au);
+		if (ret)
+			return ret;
+
+		auth->authorizer_buf = au->buf->vec.iov_base;
+		auth->authorizer_buf_len = au->buf->vec.iov_len;
 	}
 	return 0;
 }