linux-kernel - Re: [Xen-devel] [PATCH 1/1] xen/gntdev: kmalloc structure gntdev_copy

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Message-Id: <573036FA02000078000E821B@prv-mh.provo.novell.com>
Date:	Mon, 09 May 2016 00:06:34 -0600
From:	"Jan Beulich" <jbeulich@...e.com>
To:	<xypron.glpk@....de>
Cc:	<david.vrabel@...rix.com>, <xen-devel@...ts.xenproject.org>,
	<boris.ostrovsky@...cle.com>, "Juergen Gross" <JGross@...e.com>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [Xen-devel] [PATCH 1/1] xen/gntdev: kmalloc structure
 gntdev_copy_batch

>>> Heinrich Schuchardt <xypron.glpk@....de> 05/08/16 8:13 AM >>>
>--- a/drivers/xen/gntdev.c
>+++ b/drivers/xen/gntdev.c
>@@ -915,36 +915,43 @@ static int gntdev_grant_copy_seg(struct gntdev_copy_batch *batch,
>static long gntdev_ioctl_grant_copy(struct gntdev_priv *priv, void __user *u)
>{
>struct ioctl_gntdev_grant_copy copy;
>-    struct gntdev_copy_batch batch;
>+    struct gntdev_copy_batch *batch;
>unsigned int i;
>int ret = 0;
 >
>+    batch = kmalloc(sizeof(struct gntdev_copy_batch), GFP_KERNEL);
>+    if (!batch)
>+        return -ENOMEM;
>+
>if (copy_from_user(&copy, u, sizeof(copy)))
>return -EFAULT;
 
You carefully fix up all other error return paths below, but not the one above,
resulting in a memory leak.

>-  out:
>-    gntdev_put_pages(&batch);
>+failed:
>+    gntdev_put_pages(batch);
>+out:
>+    kfree(batch);

I'm not sure what the conventions are for label placement in the kernel sources,
but "out" having been indented by one space (which you ditch) avoided diff's -p
option picking up the label instead of the function head as context.

Jan