ipmi: fix use after free in _ipmi_destroy_user()

commit a92ce570c81dc0feaeb12a429b4bc65686d17967 upstream.

The intf_free() function frees the "intf" pointer so we cannot
dereference it again on the next line.

Fixes: cbb79863fc31 ("ipmi: Don't allow device module unload when in use")
Signed-off-by: Dan Carpenter <error27@gmail.com>
Message-Id: <Y3M8xa1drZv4CToE@kili>
Cc: <stable@vger.kernel.org> # 5.5+
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index d5ee52b..5d403fb 100644 (file)
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -1330,6 +1330,7 @@ static void _ipmi_destroy_user(struct ipmi_user *user)
        unsigned long    flags;
        struct cmd_rcvr  *rcvr;
        struct cmd_rcvr  *rcvrs = NULL;
+       struct module    *owner;
 
        if (!acquire_ipmi_user(user, &i)) {
                /*
@@ -1392,8 +1393,9 @@ static void _ipmi_destroy_user(struct ipmi_user *user)
                kfree(rcvr);
        }
 
+       owner = intf->owner;
        kref_put(&intf->refcount, intf_free);
-       module_put(intf->owner);
+       module_put(owner);
 }
 
 int ipmi_destroy_user(struct ipmi_user *user)