Re: [RFC][PATCH] vfs: always protect diretory file->fpos with inodemutex

[Li Zefan]

On 2013/2/19 20:33, Zheng Liu wrote:
> On Tue, Feb 19, 2013 at 09:22:40AM +0800, Li Zefan wrote:
>> There's a long long-standing bug...As long as I don't know when it dates
>> from.
>>
>> I've written and attached a simple program to reproduce this bug, and it can
>> immediately trigger the bug in my box. It uses two threads, one keeps calling
>> read(), and the other calling readdir(), both on the same directory fd.
> 
> Hi Zefan,
> 
> Out of curiosity, why do you call read(2) on a directory fd?  I only
> open(2) a directory in order to execute a flush operation to make sure
> that a file is really created.
> 

Because something wrong happened in userspace programs.

After a thread closed a socket, another thread is still reading data from
this socket, but the socket fd has been re-used for opening directory for
readdir()!

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