From: Lv Yunlong lyl2019@mail.ustc.edu.cn Sent: Tuesday, March 23, 2021 12:34 AM
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
While I think this works, a slightly better solution might be to remove all calls to kfree(info->apertures) in hvfb_getmem(), and just let framebuffer_release() handle freeing the memory. That's what is done in other drivers that follow the fbdev pattern, and it's less code overall.
Michael