Re: [PATCH] xenforeignmemory: work around bug in older privcmd

From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Paul Durrant <paul.durrant@citrix.com>, xen-devel@lists.xenproject.org
Cc: Ian Jackson <ian.jackson@eu.citrix.com>, Wei Liu <wei.liu2@citrix.com>
Subject: Re: [PATCH] xenforeignmemory: work around bug in older privcmd
Date: Tue, 28 Aug 2018 15:12:32 +0100	[thread overview]
Message-ID: <fcd947b7-844d-2ddf-71ee-45dfd6cf4566@citrix.com> (raw)
In-Reply-To: <20180824121626.27261-1-paul.durrant@citrix.com>

On 24/08/18 13:16, Paul Durrant wrote:
> diff --git a/tools/libs/foreignmemory/linux.c b/tools/libs/foreignmemory/linux.c
> index 3686cf41e0..0368aa09f4 100644
> --- a/tools/libs/foreignmemory/linux.c
> +++ b/tools/libs/foreignmemory/linux.c
> @@ -53,6 +53,23 @@ int osdep_xenforeignmemory_open(xenforeignmemory_handle *fmem)
>          return -1;
>      }
>  
> +    /*
> +     * Older versions of privcmd return -EINVAL for unimplemented ioctls
> +     * so we need to probe for the errno to use rather than just using
> +     * the conventional ENOTTY.
> +     */
> +    if ( ioctl(fd, IOCTL_PRIVCMD_UNIMPLEMENTED, NULL) >= 0 )
> +    {
> +        xtl_log(fmem->logger, XTL_ERROR, -1, "xenforeignmemory",
> +                "privcmd ioctl should not be implemented");

This error path leaks fd.

~Andrew

> +        return -1;
> +    }
> +    else
> +    {
> +        fmem->unimpl_errno = errno;
> +        errno = 0;
> +    }
> +
>      fmem->fd = fd;
>      return 0;
>  }
>

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