linux-kernel - [PATCH] VMCI: Fix dereference before NULL-check of context ptr

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Message-Id: <1584374754-9515-1-git-send-email-xiyuyang19@fudan.edu.cn>
Date:   Tue, 17 Mar 2020 00:05:51 +0800
From:   Xiyu Yang <xiyuyang19@...an.edu.cn>
To:     Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ira Weiny <ira.weiny@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexios Zavras <alexios.zavras@...el.com>,
        Mike Marshall <hubcap@...ibond.com>,
        Xiyu Yang <xiyuyang19@...an.edu.cn>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org
Cc:     yuanxzhang@...an.edu.cn, kjlu@....edu,
        Xin Tan <tanxin.ctf@...il.com>
Subject: [PATCH] VMCI: Fix dereference before NULL-check of context ptr

A NULL pointer can be returned by vmci_ctx_get(). Thus add a
corresponding check so that a NULL pointer dereference will
be avoided in vmci_ctx_put().

Signed-off-by: Xiyu Yang <xiyuyang19@...an.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@...il.com>
---
 drivers/misc/vmw_vmci/vmci_queue_pair.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/vmw_vmci/vmci_queue_pair.c b/drivers/misc/vmw_vmci/vmci_queue_pair.c
index 8531ae781195..032617101ebc 100644
--- a/drivers/misc/vmw_vmci/vmci_queue_pair.c
+++ b/drivers/misc/vmw_vmci/vmci_queue_pair.c
@@ -1859,7 +1859,8 @@ static int qp_detatch_host_work(struct vmci_handle handle)
 
 	result = vmci_qp_broker_detach(handle, context);
 
-	vmci_ctx_put(context);
+	if (context)
+		vmci_ctx_put(context);
 	return result;
 }
 
-- 
2.7.4