| From d98e4d95411bbde2220a7afa38dcc9c14d71acbe Mon Sep 17 00:00:00 2001 |
| From: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com> |
| Date: Mon, 28 Jun 2021 19:33:52 -0700 |
| Subject: ntfs: fix validity check for file name attribute |
| |
| From: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com> |
| |
| commit d98e4d95411bbde2220a7afa38dcc9c14d71acbe upstream. |
| |
| When checking the file name attribute, we want to ensure that it fits |
| within the bounds of ATTR_RECORD. To do this, we should check that (attr |
| record + file name offset + file name length) < (attr record + attr record |
| length). |
| |
| However, the original check did not include the file name offset in the |
| calculation. This means that corrupted on-disk metadata might not caught |
| by the incorrect file name check, and lead to an invalid memory access. |
| |
| An example can be seen in the crash report of a memory corruption error |
| found by Syzbot: |
| https://syzkaller.appspot.com/bug?id=a1a1e379b225812688566745c3e2f7242bffc246 |
| |
| Adding the file name offset to the validity check fixes this error and |
| passes the Syzbot reproducer test. |
| |
| Link: https://lkml.kernel.org/r/20210614050540.289494-1-desmondcheongzx@gmail.com |
| Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com> |
| Reported-by: syzbot+213ac8bb98f7f4420840@syzkaller.appspotmail.com |
| Tested-by: syzbot+213ac8bb98f7f4420840@syzkaller.appspotmail.com |
| Acked-by: Anton Altaparmakov <anton@tuxera.com> |
| Cc: Shuah Khan <skhan@linuxfoundation.org> |
| Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| Cc: <stable@vger.kernel.org> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| fs/ntfs/inode.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/fs/ntfs/inode.c |
| +++ b/fs/ntfs/inode.c |
| @@ -477,7 +477,7 @@ err_corrupt_attr: |
| } |
| file_name_attr = (FILE_NAME_ATTR*)((u8*)attr + |
| le16_to_cpu(attr->data.resident.value_offset)); |
| - p2 = (u8*)attr + le32_to_cpu(attr->data.resident.value_length); |
| + p2 = (u8 *)file_name_attr + le32_to_cpu(attr->data.resident.value_length); |
| if (p2 < (u8*)attr || p2 > p) |
| goto err_corrupt_attr; |
| /* This attribute is ok, but is it in the $Extend directory? */ |
