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Date: Fri, 10 Nov 2023 08:21:11 +0000
From: Al Viro <viro@zeniv.linux.org.uk>
To: Zizhi Wo <wozizhi@huawei.com>
Cc: brauner@kernel.org, akpm@linux-foundation.org, oleg@redhat.com,
	jlayton@kernel.org, dchinner@redhat.com, adobriyan@gmail.com,
	yang.lee@linux.alibaba.com, linux-kernel@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, yangerkun@huawei.com
Subject: Re: [PATCH next V3] proc: support file->f_pos checking in mem_lseek
Message-ID: <20231110082111.GN1957730@ZenIV>
References: <20231110151928.2667204-1-wozizhi@huawei.com>
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Sender: Al Viro <viro@ftp.linux.org.uk>

On Fri, Nov 10, 2023 at 11:19:28PM +0800, Zizhi Wo wrote:
> From: WoZ1zh1 <wozizhi@huawei.com>
> 
> In mem_lseek, file->f_pos may overflow. And it's not a problem that
> mem_open set file mode with FMODE_UNSIGNED_OFFSET(memory_lseek). However,
> another file use mem_lseek do lseek can have not FMODE_UNSIGNED_OFFSET
> (kpageflags_proc_ops/proc_pagemap_operations...), so in order to prevent
> file->f_pos updated to an abnormal number, fix it by checking overflow and
> FMODE_UNSIGNED_OFFSET.

1) How is that different from the previous version?
2) Would FMODE_UNSIGNED_OFFSET be wrong for those files?  If not, why not?