Re: [PATCH 4/4] quota: simplify the quotactl compat handling
From: Christoph Hellwig <hch@lst.de>
Date: 2020-07-26 16:34:29
Also in:
linux-arch, linux-arm-kernel, linux-fsdevel, lkml
On Sun, Jul 26, 2020 at 05:32:14PM +0100, Al Viro wrote:
quoted
+static int compat_copy_fs_qfilestat(struct compat_fs_qfilestat __user *to, + struct fs_qfilestat *from) +{ + if (copy_to_user(to, from, sizeof(*to)) || + put_user(from->qfs_nextents, &to->qfs_nextents)) + return -EFAULT; + return 0; +}do we have any need of that put_user()? Note that you don't even call that thing unless compat_need_64bit_alignment_fixup() is true. And AFAICS all such cases are little-endian...
The main reason it is there is to preserve the previous semantics. And no, I don't think we actually need it on x86. But what if some poor souls adds a BE version that needs this? E.g. arm oabi has similar weird alignment, and now imagine someone adding arm64 compat code for that..