2022-11-14 14:00:43

by Abdun Nihaal

Subject: [PATCH v2] 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: [email protected]
Fixes: 82cae269cfa9 ("fs/ntfs3: Add initialization of super block")
Signed-off-by: Abdun Nihaal <[email protected]>
---

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

2022-12-26 15:52:58

by Konstantin Komarov

Subject: Re: [PATCH v2] fs/ntfs3: Validate attribute data and valid sizes

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: [email protected]
> Fixes: 82cae269cfa9 ("fs/ntfs3: Add initialization of super block")
> Signed-off-by: Abdun Nihaal <[email protected]>
> ---
>
> 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.