linux-kernel - [PATCH] fs/ntfs3: Validate attribute data and valid sizes

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Message-Id: <20221004031502.20007-1-abdun.nihaal@gmail.com>
Date:   Tue,  4 Oct 2022 08:45:02 +0530
From:   Abdun Nihaal <abdun.nihaal@...il.com>
To:     almaz.alexandrovich@...agon-software.com
Cc:     ntfs3@...ts.linux.dev, linux-kernel@...r.kernel.org,
        skhan@...uxfoundation.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        Abdun Nihaal <abdun.nihaal@...il.com>,
        syzbot+fa4648a5446460b7b963@...kaller.appspotmail.com
Subject: [PATCH] fs/ntfs3: Validate attribute data and valid sizes

The data_size and valid_size fields of non resident attributes should be
less than the its alloc_size field, but this is not checked in
ntfs_read_mft function.

Syzbot reports a allocation order warning due to a large unchecked value
of data_size getting assigned to inode->i_size which is then passed to
kcalloc.

Add sanity check for ensuring that the data_size and valid_size fields
are not larger than alloc_size field.

Link: https://syzkaller.appspot.com/bug?extid=fa4648a5446460b7b963
Reported-and-tested-by: syzbot+fa4648a5446460b7b963@...kaller.appspotmail.com
Fixes: (82cae269cfa95) fs/ntfs3: Add initialization of super block
Signed-off-by: Abdun Nihaal <abdun.nihaal@...il.com>
---
 fs/ntfs3/inode.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/ntfs3/inode.c b/fs/ntfs3/inode.c
index e9cf00d14733..9c244029be75 100644
--- a/fs/ntfs3/inode.c
+++ b/fs/ntfs3/inode.c
@@ -132,6 +132,13 @@ static struct inode *ntfs_read_mft(struct inode *inode,
 	if (le16_to_cpu(attr->name_off) + attr->name_len > asize)
 		goto out;
 
+	if (attr->non_res) {
+		t64 = le64_to_cpu(attr->nres.alloc_size);
+		if (le64_to_cpu(attr->nres.data_size) > t64 ||
+		    le64_to_cpu(attr->nres.valid_size) > t64)
+			goto out;
+	}
+
 	switch (attr->type) {
 	case ATTR_STD:
 		if (attr->non_res ||
-- 
2.37.3