Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Lv Yunlong <lyl2019@mail.ustc.edu.cn>
To:     kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com,
        wei.liu@kernel.org
Cc:     linux-hyperv@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Subject: [PATCH] video/fbdev: Fix a double free in hvfb_probe
Date:   Tue, 23 Mar 2021 00:33:50 -0700
Message-Id: <20210323073350.17697-1-lyl2019@mail.ustc.edu.cn>
MIME-Version: 1.0
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In function hvfb_probe in hyperv_fb.c, it calls hvfb_getmem(hdev, info)
and return err when info->apertures is freed.

In the error1 label of hvfb_probe, info->apertures will be freed twice
by framebuffer_release(info).

My patch sets info->apertures to NULL after it was freed to avoid
double free.

Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
---
 drivers/video/fbdev/hyperv_fb.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c
index c8b0ae676809..2fc9b507e73a 100644
--- a/drivers/video/fbdev/hyperv_fb.c
+++ b/drivers/video/fbdev/hyperv_fb.c
@@ -1032,6 +1032,7 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info)
 		if (!pdev) {
 			pr_err("Unable to find PCI Hyper-V video\n");
 			kfree(info->apertures);
+			info->apertures = NULL;
 			return -ENODEV;
 		}
 
@@ -1130,6 +1131,7 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info)
 		pci_dev_put(pdev);
 	}
 	kfree(info->apertures);
+	info->apertures = NULL;
 
 	return 0;
 
@@ -1142,6 +1144,7 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info)
 	if (!gen2vm)
 		pci_dev_put(pdev);
 	kfree(info->apertures);
+	info->apertures = NULL;
 
 	return -ENOMEM;
 }
-- 
2.25.1