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Re: [Qemu-block] [Qemu-devel] [PATCH v4] file-posix: specify expected fi

From: John Snow
Subject: Re: [Qemu-block] [Qemu-devel] [PATCH v4] file-posix: specify expected filetypes
Date: Wed, 31 Jan 2018 13:39:48 -0500
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2


On 01/19/2018 06:03 PM, Eric Blake wrote:
> On 01/19/2018 04:47 PM, John Snow wrote:
>> Adjust each caller of raw_open_common to specify if they are expecting
>> host and character devices or not. Tighten expectations of file types upon
>> open in the common code and refuse types that are not expected.
>> This has two effects:
>> (1) Character and block devices are now considered deprecated for the
>>     'file' driver, which expects only S_IFREG, and
>> (2) no file-posix driver (file, host_cdrom, or host_device) can open
>>     directories now.
>> I don't think there's a legitimate reason to open directories as if
>> they were files. This prevents QEMU from opening and attempting to probe
>> a directory inode, which can break in exciting ways. One of those ways
>> is lseek on ext4/xfs, which will return 0x7fffffffffffffff as the file
>> size instead of EISDIR. This can coax QEMU into responding with a
>> confusing "file too big" instead of "Hey, that's not a file".
>> See: https://bugs.launchpad.net/qemu/+bug/1739304/
>> Signed-off-by: John Snow <address@hidden>
>> ---
> Reviewed-by: Eric Blake <address@hidden>

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