From: Dan Carpenter <error27@gmail.com>
Date: Tue, 15 Nov 2022 13:17:43 +0000 (+0300)
Subject: ipmi: fix use after free in _ipmi_destroy_user()
X-Git-Tag: v5.15.92~613
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=bfce073089cb81482521c65061835aaa6d1a6cc0;p=platform%2Fkernel%2Flinux-rpi.git

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 8dbc349..15c211c 100644
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -1273,6 +1273,7 @@ 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)) {
 		/*
@@ -1334,8 +1335,9 @@ 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)