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Date: Fri, 24 May 2019 14:11:34 +0800 From: "cgxu519@...o.com.cn" <cgxu519@...o.com.cn> To: Jan Kara <jack@...e.cz> Cc: jack@...e.com, linux-ext4@...r.kernel.org Subject: Re: [PATCH] ext2: strengthen value length check in ext2_xattr_set() On Wed, 2019-05-22 at 11:50 +0200, Jan Kara wrote: > On Wed 22-05-19 16:28:46, Chengguang Xu wrote: > > Actually maximum length of a valid entry value is not > > ->s_blocksize because header, last entry and entry > > name will also occupy some spaces. This patch > > strengthens the value length check and return -ERANGE > > when the length is larger than allowed maximum length. > > > > Signed-off-by: Chengguang Xu <cgxu519@...o.com.cn> > > Thanks for the patch! But what's the point of this change? We would return > ERANGE instead of ENOSPC? I don't think that's serious enough to warrant > changing existing behavior... Hi Jan, Instead of adding the check here, I propose to change value size limit check in ext2_xattr_entry_valid(). size = le32_to_cpu(entry->e_value_size); if (size > end_offs || le16_to_cpu(entry->e_value_offs) + size > end_offs) Change to size = EXT2_XATTR_SIZE(le32_to_cpu(entry->e_value_size)); if (size >= end_offs - sizeof(struct ext2_xattr_header) - sizeof(__u32) || le16_to_cpu(entry->e_value_offs) + size > end_offs) Will you agree this change? Thanks, Chengguang
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