Re: [PATCH] ext4: Fix data corruption for mmap writes

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On Thu, May 25, 2017 at 01:46:22PM +0200, Jan Kara wrote:
> mpage_submit_page() can race with another process growing i_size and
> writing data via mmap to the written-back page. As mpage_submit_page()
> samples i_size too early, it may happen that ext4_bio_write_page()
> zeroes out too large tail of the page and thus corrupts user data.
> 
> Fix the problem by sampling i_size only after the page has been
> write-protected in page tables by clear_page_dirty_for_io() call.
> 
> Reported-by: Michael Zimmer <michael@xxxxxxxxxxx>
> CC: stable@xxxxxxxxxxxxxxx
> Fixes: cb20d5188366f04d96d2e07b1240cc92170ade40
> Signed-off-by: Jan Kara <jack@xxxxxxx>

Thanks, applied.

					- Ted



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