From 1738bcf9e652010decd3355fa5a6b6985e175a37 Mon Sep 17 00:00:00 2001 From: Desmond Cheong Zhi Xi Date: Mon, 28 Jun 2021 19:33:52 -0700 Subject: [PATCH] ntfs: fix validity check for file name attribute 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 Reported-by: syzbot+213ac8bb98f7f4420840@syzkaller.appspotmail.com Tested-by: syzbot+213ac8bb98f7f4420840@syzkaller.appspotmail.com Acked-by: Anton Altaparmakov Cc: Shuah Khan Cc: Greg Kroah-Hartman Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/ntfs/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/ntfs/inode.c b/fs/ntfs/inode.c index e9d5c8e638b0..ea18e4a2a691 100644 --- a/fs/ntfs/inode.c +++ b/fs/ntfs/inode.c @@ -477,7 +477,7 @@ static int ntfs_is_extended_system_file(ntfs_attr_search_ctx *ctx) } 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? */