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* [PATCH v2] ntfs: Ensure $Extend is a directory
@ 2022-07-27  0:15 Soumya Negi
  2022-08-29 15:03 ` Soumya Negi
  0 siblings, 1 reply; 3+ messages in thread
From: Soumya Negi @ 2022-07-27  0:15 UTC (permalink / raw)
  To: Anton Altaparmakov, Shuah Khan
  Cc: linux-ntfs-dev, linux-kernel-mentees, linux-kernel, stable

Fix Syzbot bug: kernel BUG in ntfs_lookup_inode_by_name
https://syzkaller.appspot.com/bug?id=32cf53b48c1846ffc25a185a2e92e170d1a95d71

Check whether $Extend is a directory or not( for NTFS3.0+) while
loading system files. If it isn't(as in the case of this bug where the
mft record for $Extend contains a regular file), load_system_files()
returns false.

Reported-by: syzbot+30b7f850c6d98ea461d2@syzkaller.appspotmail.com
CC: stable@vger.kernel.org # 4.9+
Signed-off-by: Soumya Negi <soumya.negi97@gmail.com>
---
Changes since v1:
* Added CC tag for stable
* Formatted changelog to fit within 72 cols

---
 fs/ntfs/super.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/ntfs/super.c b/fs/ntfs/super.c
index 5ae8de09b271..18e2902531f9 100644
--- a/fs/ntfs/super.c
+++ b/fs/ntfs/super.c
@@ -2092,10 +2092,15 @@ static bool load_system_files(ntfs_volume *vol)
 	// TODO: Initialize security.
 	/* Get the extended system files' directory inode. */
 	vol->extend_ino = ntfs_iget(sb, FILE_Extend);
-	if (IS_ERR(vol->extend_ino) || is_bad_inode(vol->extend_ino)) {
+	if (IS_ERR(vol->extend_ino) || is_bad_inode(vol->extend_ino) ||
+	    !S_ISDIR(vol->extend_ino->i_mode)) {
+		static const char *es1 = "$Extend is not a directory";
+		static const char *es2 = "Failed to load $Extend";
+		const char *es = !S_ISDIR(vol->extend_ino->i_mode) ? es1 : es2;
+
 		if (!IS_ERR(vol->extend_ino))
 			iput(vol->extend_ino);
-		ntfs_error(sb, "Failed to load $Extend.");
+		ntfs_error(sb, "%s.", es);
 		goto iput_sec_err_out;
 	}
 #ifdef NTFS_RW
-- 
2.17.1

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^ permalink raw reply related	[flat|nested] 3+ messages in thread

* Re: [PATCH v2] ntfs: Ensure $Extend is a directory
  2022-07-27  0:15 [PATCH v2] ntfs: Ensure $Extend is a directory Soumya Negi
@ 2022-08-29 15:03 ` Soumya Negi
  2023-05-11  7:55   ` Namjae Jeon
  0 siblings, 1 reply; 3+ messages in thread
From: Soumya Negi @ 2022-08-29 15:03 UTC (permalink / raw)
  To: Anton Altaparmakov, Shuah Khan
  Cc: linux-ntfs-dev, linux-kernel-mentees, linux-kernel, stable

On Tue, Jul 26, 2022 at 05:15:13PM -0700, Soumya Negi wrote:
> Fix Syzbot bug: kernel BUG in ntfs_lookup_inode_by_name
> https://syzkaller.appspot.com/bug?id=32cf53b48c1846ffc25a185a2e92e170d1a95d71
> 
> Check whether $Extend is a directory or not( for NTFS3.0+) while
> loading system files. If it isn't(as in the case of this bug where the
> mft record for $Extend contains a regular file), load_system_files()
> returns false.
> 
> Reported-by: syzbot+30b7f850c6d98ea461d2@syzkaller.appspotmail.com
> CC: stable@vger.kernel.org # 4.9+
> Signed-off-by: Soumya Negi <soumya.negi97@gmail.com>
> ---
> Changes since v1:
> * Added CC tag for stable
> * Formatted changelog to fit within 72 cols
> 
> ---
>  fs/ntfs/super.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ntfs/super.c b/fs/ntfs/super.c
> index 5ae8de09b271..18e2902531f9 100644
> --- a/fs/ntfs/super.c
> +++ b/fs/ntfs/super.c
> @@ -2092,10 +2092,15 @@ static bool load_system_files(ntfs_volume *vol)
>  	// TODO: Initialize security.
>  	/* Get the extended system files' directory inode. */
>  	vol->extend_ino = ntfs_iget(sb, FILE_Extend);
> -	if (IS_ERR(vol->extend_ino) || is_bad_inode(vol->extend_ino)) {
> +	if (IS_ERR(vol->extend_ino) || is_bad_inode(vol->extend_ino) ||
> +	    !S_ISDIR(vol->extend_ino->i_mode)) {
> +		static const char *es1 = "$Extend is not a directory";
> +		static const char *es2 = "Failed to load $Extend";
> +		const char *es = !S_ISDIR(vol->extend_ino->i_mode) ? es1 : es2;
> +
>  		if (!IS_ERR(vol->extend_ino))
>  			iput(vol->extend_ino);
> -		ntfs_error(sb, "Failed to load $Extend.");
> +		ntfs_error(sb, "%s.", es);
>  		goto iput_sec_err_out;
>  	}
>  #ifdef NTFS_RW
> -- 
> 2.17.1

Hi Anton,
Have you had a chance to look at this patch?

Thanks,
Soumya

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https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH v2] ntfs: Ensure $Extend is a directory
  2022-08-29 15:03 ` Soumya Negi
@ 2023-05-11  7:55   ` Namjae Jeon
  0 siblings, 0 replies; 3+ messages in thread
From: Namjae Jeon @ 2023-05-11  7:55 UTC (permalink / raw)
  To: Soumya Negi
  Cc: Christian Brauner, linux-ntfs-dev, linux-kernel,
	linux-kernel-mentees, Anton Altaparmakov

2022-08-30 0:03 GMT+09:00, Soumya Negi <soumya.negi97@gmail.com>:
> On Tue, Jul 26, 2022 at 05:15:13PM -0700, Soumya Negi wrote:
>> Fix Syzbot bug: kernel BUG in ntfs_lookup_inode_by_name
>> https://syzkaller.appspot.com/bug?id=32cf53b48c1846ffc25a185a2e92e170d1a95d71
>>
>> Check whether $Extend is a directory or not( for NTFS3.0+) while
>> loading system files. If it isn't(as in the case of this bug where the
>> mft record for $Extend contains a regular file), load_system_files()
>> returns false.
>>
>> Reported-by: syzbot+30b7f850c6d98ea461d2@syzkaller.appspotmail.com
>> CC: stable@vger.kernel.org # 4.9+
>> Signed-off-by: Soumya Negi <soumya.negi97@gmail.com>
>> ---
>> Changes since v1:
>> * Added CC tag for stable
>> * Formatted changelog to fit within 72 cols
>>
>> ---
>>  fs/ntfs/super.c | 9 +++++++--
>>  1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/ntfs/super.c b/fs/ntfs/super.c
>> index 5ae8de09b271..18e2902531f9 100644
>> --- a/fs/ntfs/super.c
>> +++ b/fs/ntfs/super.c
>> @@ -2092,10 +2092,15 @@ static bool load_system_files(ntfs_volume *vol)
>>  	// TODO: Initialize security.
>>  	/* Get the extended system files' directory inode. */
>>  	vol->extend_ino = ntfs_iget(sb, FILE_Extend);
>> -	if (IS_ERR(vol->extend_ino) || is_bad_inode(vol->extend_ino)) {
>> +	if (IS_ERR(vol->extend_ino) || is_bad_inode(vol->extend_ino) ||
>> +	    !S_ISDIR(vol->extend_ino->i_mode)) {
>> +		static const char *es1 = "$Extend is not a directory";
>> +		static const char *es2 = "Failed to load $Extend";
>> +		const char *es = !S_ISDIR(vol->extend_ino->i_mode) ? es1 : es2;
>> +
>>  		if (!IS_ERR(vol->extend_ino))
>>  			iput(vol->extend_ino);
>> -		ntfs_error(sb, "Failed to load $Extend.");
>> +		ntfs_error(sb, "%s.", es);
>>  		goto iput_sec_err_out;
>>  	}
>>  #ifdef NTFS_RW
>> --
>> 2.17.1
>
> Hi Anton,
> Have you had a chance to look at this patch?
Hi,

Could you elaborate more ? Isn't MFT_RECORD_IS_DIRECTORY flags set in
mft record of $Extend ?

> Thanks,
> Soumya
>
>
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^ permalink raw reply	[flat|nested] 3+ messages in thread

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2022-08-29 15:03 ` Soumya Negi
2023-05-11  7:55   ` Namjae Jeon

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