linux-kernel - [PATCH v2] VMCI: Fix NULL pointer dereference on context ptr

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Message-Id: <1584951832-120773-1-git-send-email-xiyuyang19@fudan.edu.cn>
Date:   Mon, 23 Mar 2020 16:22:33 +0800
From:   Xiyu Yang <xiyuyang19@...an.edu.cn>
To:     Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alexios Zavras <alexios.zavras@...el.com>,
        Allison Randal <allison@...utok.net>,
        Adit Ranadive <aditr@...are.com>,
        Jorgen Hansen <jhansen@...are.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vishnu DASA <vdasa@...are.com>,
        Xiyu Yang <xiyuyang19@...an.edu.cn>,
        linux-kernel@...r.kernel.org
Cc:     yuanxzhang@...an.edu.cn, kjlu@....edu,
        Xin Tan <tanxin.ctf@...il.com>
Subject: [PATCH v2] VMCI: Fix NULL pointer dereference on context ptr

A NULL vmci_ctx object may pass to vmci_ctx_put() from its callers.
Add a NULL check to prevent NULL pointer dereference.

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

diff --git a/drivers/misc/vmw_vmci/vmci_context.c b/drivers/misc/vmw_vmci/vmci_context.c
index 16695366ec92..2f4963ab51bd 100644
--- a/drivers/misc/vmw_vmci/vmci_context.c
+++ b/drivers/misc/vmw_vmci/vmci_context.c
@@ -494,7 +494,8 @@ static void ctx_free_ctx(struct kref *kref)
  */
 void vmci_ctx_put(struct vmci_ctx *context)
 {
-	kref_put(&context->kref, ctx_free_ctx);
+	if (context)
+		kref_put(&context->kref, ctx_free_ctx);
 }
 
 /*
-- 
2.7.4