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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,
	Lv Yunlong <lyl2019@mail.ustc.edu.cn>,
	linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org,
	linux-kernel@vger.kernel.org
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> (raw)

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


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Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-23  7:33 Lv Yunlong [this message]
2021-03-23 11:28 ` Wei Liu
2021-03-23 18:52 ` Michael Kelley
2021-03-24 10:24   ` lyl2019

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