From: Yuezhang Mo <Yuezhang.Mo@sony.com>
Date: Thu, 17 Oct 2024 01:25:06 +0000 (+0800)
Subject: exfat: fix file being changed by unaligned direct write
X-Git-Tag: v6.13-rc1~45^2~7
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2e94e5bb94a3e641a25716a560bf474225fda83c;p=thirdparty%2Flinux.git

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 <Yuezhang.Mo@sony.com>
Co-developed-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
---

diff --git a/fs/exfat/file.c b/fs/exfat/file.c
index a25d7eb789f4c..fb38769c3e39d 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) {