From: Wei Liu <wei.liu@kernel.org> To: Lv Yunlong <lyl2019@mail.ustc.edu.cn> Cc: kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com, wei.liu@kernel.org, linux-hyperv@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] video/fbdev: Fix a double free in hvfb_probe Date: Tue, 23 Mar 2021 11:28:38 +0000 [thread overview] Message-ID: <20210323112838.xrastmol4fnxqxub@liuwe-devbox-debian-v2> (raw) In-Reply-To: <20210323073350.17697-1-lyl2019@mail.ustc.edu.cn> Thanks for your patch. I would like to change the prefix to "video: hyperv_fb:" to be more specific. On Tue, Mar 23, 2021 at 12:33:50AM -0700, Lv Yunlong wrote: > 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). > I would say "freed for the second time" here. What you wrote reads to me fraembuffer_release frees the buffer twice all by itself. > My patch sets info->apertures to NULL after it was freed to avoid > double free. > I think this approach works. I would like to give other people a chance to comment though. Fixes: 3a6fb6c4255c ("video: hyperv: hyperv_fb: Use physical memory for fb on HyperV Gen 1 VMs.") > 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 > >
WARNING: multiple messages have this Message-ID (diff)
From: Wei Liu <wei.liu@kernel.org> To: Lv Yunlong <lyl2019@mail.ustc.edu.cn> Cc: wei.liu@kernel.org, sthemmin@microsoft.com, haiyangz@microsoft.com, linux-hyperv@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org, kys@microsoft.com Subject: Re: [PATCH] video/fbdev: Fix a double free in hvfb_probe Date: Tue, 23 Mar 2021 11:28:38 +0000 [thread overview] Message-ID: <20210323112838.xrastmol4fnxqxub@liuwe-devbox-debian-v2> (raw) In-Reply-To: <20210323073350.17697-1-lyl2019@mail.ustc.edu.cn> Thanks for your patch. I would like to change the prefix to "video: hyperv_fb:" to be more specific. On Tue, Mar 23, 2021 at 12:33:50AM -0700, Lv Yunlong wrote: > 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). > I would say "freed for the second time" here. What you wrote reads to me fraembuffer_release frees the buffer twice all by itself. > My patch sets info->apertures to NULL after it was freed to avoid > double free. > I think this approach works. I would like to give other people a chance to comment though. Fixes: 3a6fb6c4255c ("video: hyperv: hyperv_fb: Use physical memory for fb on HyperV Gen 1 VMs.") > 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 > > _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2021-03-23 11:29 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-03-23 7:33 [PATCH] video/fbdev: Fix a double free in hvfb_probe Lv Yunlong 2021-03-23 7:33 ` Lv Yunlong 2021-03-23 11:28 ` Wei Liu [this message] 2021-03-23 11:28 ` Wei Liu 2021-03-23 18:52 ` Michael Kelley 2021-03-23 18:52 ` Michael Kelley 2021-03-24 10:24 ` lyl2019 2021-03-24 10:24 ` lyl2019
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