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@syzkaller.appspotmail.com
Fixes: 82cae269cfa9 ("fs/ntfs3: Add initialization of super block")
Signed-off-by: Abdun Nihaal <abdun.nihaal@gmail.com>
---

Please apply this instead of my previous patch.

Changes in v2:
 Correct the format used for the Fixes tag.

 fs/ntfs3/inode.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/ntfs3/inode.c b/fs/ntfs3/inode.c
index 970bb7c357c7..763dd982a43a 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

On 14.11.2022 15:53, Abdun Nihaal wrote:
> 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@syzkaller.appspotmail.com
> Fixes: 82cae269cfa9 ("fs/ntfs3: Add initialization of super block")
> Signed-off-by: Abdun Nihaal <abdun.nihaal@gmail.com>
> ---
>
> Please apply this instead of my previous patch.
>
> Changes in v2:
>   Correct the format used for the Fixes tag.
>
>   fs/ntfs3/inode.c | 7 +++++++
>   1 file changed, 7 insertions(+)
>
> diff --git a/fs/ntfs3/inode.c b/fs/ntfs3/inode.c
> index 970bb7c357c7..763dd982a43a 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 ||
Hello. Your patch has been already applied.