ipmi: fix refcount leak in i_ipmi_request()

When a caller provides a `supplied_recv` message to i_ipmi_request(),
the function increments the user's `nr_msgs` reference count. If an
error occurs later, the out_err cleanup path only frees the recv_msg
if the function allocated it itself (i.e., !supplied_recv). In the
supplied_recv case the cleanup is skipped, leaving the reference count
elevated. The caller ipmi_request_supply_msgs() does not release the
supplied_recv on error, so the reference is permanently leaked.

Fix this by explicitly reverting the reference count operations when a
supplied recv_msg with a valid user pointer is present in the error
path: decrement nr_msgs and drop the user's kref.

Cc: stable@vger.kernel.org
Fixes: b52da4054ee0 ("ipmi: Rework user message limit handling")
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
Message-ID: <20260603120634.3758747-1-vulab@iscas.ac.cn>
Signed-off-by: Corey Minyard <corey@minyard.net>

diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index 7ca2cacbaa051230ae2ff1961182ca8fa3f41265..ab4c85f3d6fe8f502601ebf93c988b42e372b50f 100644 (file)
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -2345,6 +2345,10 @@ static int i_ipmi_request(struct ipmi_user     *user,
                if (smi_msg == NULL) {
                        if (!supplied_recv)
                                ipmi_free_recv_msg(recv_msg);
+                       else if (recv_msg->user) {
+                               atomic_dec(&recv_msg->user->nr_msgs);
+                               kref_put(&recv_msg->user->refcount, free_ipmi_user);
+                       }
                        return -ENOMEM;
                }
        }
@@ -2418,6 +2422,10 @@ out_err:
                        ipmi_free_smi_msg(smi_msg);
                if (!supplied_recv)
                        ipmi_free_recv_msg(recv_msg);
+               else if (recv_msg->user) {
+                       atomic_dec(&recv_msg->user->nr_msgs);
+                       kref_put(&recv_msg->user->refcount, free_ipmi_user);
+               }
        }
        return rv;
 }