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From: Lizhi Xu <lizhi.xu@windriver.com>
To: <syzbot+a426cde6dee8c2884b0b@syzkaller.appspotmail.com>
CC: <almaz.alexandrovich@paragon-software.com>,
        <linux-fsdevel@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <ntfs3@lists.linux.dev>, <syzkaller-bugs@googlegroups.com>
Subject: [PATCH] fs/ntfs3: fix oob in mi_enum_attr
Date: Fri, 2 Feb 2024 11:33:34 +0800
Message-ID: <20240202033334.1784409-1-lizhi.xu@windriver.com>
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When the value of attr->size is too large, it can cause overflow when taking
the next attr. Here, off is used to determine the offset first to avoid problems.

Reported-and-tested-by: syzbot+a426cde6dee8c2884b0b@syzkaller.appspotmail.com
Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com>
---
 fs/ntfs3/record.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/ntfs3/record.c b/fs/ntfs3/record.c
index 53629b1f65e9..a435df98c2b1 100644
--- a/fs/ntfs3/record.c
+++ b/fs/ntfs3/record.c
@@ -243,14 +243,14 @@ struct ATTRIB *mi_enum_attr(struct mft_inode *mi, struct ATTRIB *attr)
 		off += asize;
 	}
 
-	asize = le32_to_cpu(attr->size);
-
 	/* Can we use the first field (attr->type). */
 	if (off + 8 > used) {
 		static_assert(ALIGN(sizeof(enum ATTR_TYPE), 8) == 8);
 		return NULL;
 	}
 
+	asize = le32_to_cpu(attr->size);
+
 	if (attr->type == ATTR_END) {
 		/* End of enumeration. */
 		return NULL;
-- 
2.43.0