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Message-ID: <1453845246.2633.17.camel@slavad-ubuntu-14.04>
Subject: Re: [patch] hfs: fix hfs_readdir()
From: Viacheslav Dubeyko <slava@dubeyko.com>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Chengyu Song <csong84@gatech.edu>,
        Andrew Morton <akpm@linux-foundation.org>,
        David Howells <dhowells@redhat.com>, Al Viro <viro@zeniv.linux.org.uk>,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        kernel-janitors@vger.kernel.org
Date: Tue, 26 Jan 2016 13:54:06 -0800
In-Reply-To: <20160126191835.GD5273@mwanda>
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On Tue, 2016-01-26 at 22:18 +0300, Dan Carpenter wrote:
> Hm, I completely didn't see that it was a union instead of a struct.  I
> still think my fix is actually correct though.  Now that you point out
> the union, I see that my change is equivalent to just removing the '&'
> char.
> 
> -	memcpy(&rd->key, &fd.key, sizeof(struct hfs_cat_key));
> +	memcpy(&rd->key, fd.key, sizeof(struct hfs_cat_key));
> 

Yeahh, it looks correct right now. The rd is the pointer that includes
struct hfs_cat_key object. So, we need to use &rd->key. But on another
side we have struct hfs_find_data object on the stack. And this object
includes the pointer on union btree_key. We want to copy struct
hfs_cat_key object and we should use sizeof(struct hfs_cat_key).

> We don't want to copy sizeof(*fd.key) because that would write past the
> end of the destination struct.
> 
> On Tue, Jan 26, 2016 at 10:18:56AM -0800, Viacheslav Dubeyko wrote:
> > Another worry could be the "search_key" field of the struct
> > hfs_find_data.
> 
> I don't understand what you mean here.
> 

I mean here that we could have another incorrect copy operations for
"search_key" field. That's all.

Thanks,
Vyacheslav Dubeyko.