Re: [1/6] f2fs: check entire encrypted bigname when finding a dentry

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On Mon, Apr 24, 2017 at 10:00:08AM -0700, Eric Biggers wrote:
> From: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> 
> If user has no key under an encrypted dir, fscrypt gives digested dentries.
> Previously, when looking up a dentry, f2fs only checks its hash value with
> first 4 bytes of the digested dentry, which didn't handle hash collisions fully.
> This patch enhances to check entire dentry bytes likewise ext4.
> 
> Eric reported how to reproduce this issue by:
> 
>  # seq -f "edir/abcdefghijklmnopqrstuvwxyz012345%.0f" 100000 | xargs touch
>  # find edir -type f | xargs stat -c %i | sort | uniq | wc -l
> 100000
>  # sync
>  # echo 3 > /proc/sys/vm/drop_caches
>  # keyctl new_session
>  # find edir -type f | xargs stat -c %i | sort | uniq | wc -l
> 99999
> 
> Cc: <stable@xxxxxxxxxxxxxxx>
> Reported-by: Eric Biggers <ebiggers@xxxxxxxxxx>
> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> (fixed f2fs_dentry_hash() to work even when the hash is 0)
> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>

Thanks, applied to the fscrypt tree.

					- Ted



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