From 2e94e5bb94a3e641a25716a560bf474225fda83c Mon Sep 17 00:00:00 2001 From: Yuezhang Mo Date: Thu, 17 Oct 2024 09:25:06 +0800 Subject: [PATCH] exfat: fix file being changed by unaligned direct write Unaligned direct writes are invalid and should return an error without making any changes, rather than extending ->valid_size and then returning an error. Therefore, alignment checking is required before extending ->valid_size. Fixes: 11a347fb6cef ("exfat: change to get file size from DataLength") Signed-off-by: Yuezhang Mo Co-developed-by: Namjae Jeon Signed-off-by: Namjae Jeon --- fs/exfat/file.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/fs/exfat/file.c b/fs/exfat/file.c index a25d7eb789f4..fb38769c3e39 100644 --- a/fs/exfat/file.c +++ b/fs/exfat/file.c @@ -584,6 +584,16 @@ static ssize_t exfat_file_write_iter(struct kiocb *iocb, struct iov_iter *iter) if (ret < 0) goto unlock; + if (iocb->ki_flags & IOCB_DIRECT) { + unsigned long align = pos | iov_iter_alignment(iter); + + if (!IS_ALIGNED(align, i_blocksize(inode)) && + !IS_ALIGNED(align, bdev_logical_block_size(inode->i_sb->s_bdev))) { + ret = -EINVAL; + goto unlock; + } + } + if (pos > valid_size) { ret = exfat_extend_valid_size(file, pos); if (ret < 0 && ret != -ENOSPC) {