From 63095f4f3af59322bea984a6ae44337439348fe0 Mon Sep 17 00:00:00 2001
From: Hawkins Jiawei <yin31149@gmail.com>
Date: Thu, 1 Sep 2022 00:09:38 +0800
Subject: [PATCH] ntfs: check overflow when iterating ATTR_RECORDs
Git-commit: 63095f4f3af59322bea984a6ae44337439348fe0
Patch-mainline: v6.1-rc1
References: git-fixes
Kernel iterates over ATTR_RECORDs in mft record in ntfs_attr_find().
Because the ATTR_RECORDs are next to each other, kernel can get the next
ATTR_RECORD from end address of current ATTR_RECORD, through current
ATTR_RECORD length field.
The problem is that during iteration, when kernel calculates the end
address of current ATTR_RECORD, kernel may trigger an integer overflow bug
in executing `a = (ATTR_RECORD*)((u8*)a + le32_to_cpu(a->length))`. This
may wrap, leading to a forever iteration on 32bit systems.
This patch solves it by adding some checks on calculating end address
of current ATTR_RECORD during iteration.
Link: https://lkml.kernel.org/r/20220831160935.3409-4-yin31149@gmail.com
Link: https://lore.kernel.org/all/20220827105842.GM2030@kadam/
Signed-off-by: Hawkins Jiawei <yin31149@gmail.com>
Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Anton Altaparmakov <anton@tuxera.com>
Cc: chenxiaosong (A) <chenxiaosong2@huawei.com>
Cc: syzkaller-bugs <syzkaller-bugs@googlegroups.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Anthony Iliopoulos <ailiop@suse.com>
---
fs/ntfs/attrib.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c
index cec4be2a2d23..a3865bc4a0c6 100644
--- a/fs/ntfs/attrib.c
+++ b/fs/ntfs/attrib.c
@@ -617,6 +617,14 @@ static int ntfs_attr_find(const ATTR_TYPE type, const ntfschar *name,
return -ENOENT;
if (unlikely(!a->length))
break;
+
+ /* check whether ATTR_RECORD's length wrap */
+ if ((u8 *)a + le32_to_cpu(a->length) < (u8 *)a)
+ break;
+ /* check whether ATTR_RECORD's length is within bounds */
+ if ((u8 *)a + le32_to_cpu(a->length) > mrec_end)
+ break;
+
if (a->type != type)
continue;
/*
--
2.43.2