2019-06-17 06:58:02

by houjingyi

Subject: [PATCH] net: remove duplicate fetch in sock_getsockopt

In sock_getsockopt(), 'optlen' is fetched the first time from userspace.
'len < 0' is then checked. Then in condition 'SO_MEMINFO', 'optlen' is
fetched the second time from userspace.

If change it between two fetches may cause security problems or unexpected
behaivor, and there is no reason to fetch it a second time.

To fix this, we need to remove the second fetch.

Signed-off-by: JingYi Hou <[email protected]>
---
net/core/sock.c | 3 ---
1 file changed, 3 deletions(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index 2b3701958486..932bcbf2d565 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1477,9 +1477,6 @@ int sock_getsockopt(struct socket *sock, int level, int optname,
{
u32 meminfo[SK_MEMINFO_VARS];

- if (get_user(len, optlen))
- return -EFAULT;
-
sk_get_meminfo(sk, meminfo);

len = min_t(unsigned int, len, sizeof(meminfo));
--
2.20.1

2019-06-18 17:05:25

by David Miller

Subject: Re: [PATCH] net: remove duplicate fetch in sock_getsockopt

From: JingYi Hou <[email protected]>
Date: Mon, 17 Jun 2019 14:56:05 +0800

> In sock_getsockopt(), 'optlen' is fetched the first time from userspace.
> 'len < 0' is then checked. Then in condition 'SO_MEMINFO', 'optlen' is
> fetched the second time from userspace.
>
> If change it between two fetches may cause security problems or unexpected
> behaivor, and there is no reason to fetch it a second time.
>
> To fix this, we need to remove the second fetch.
>
> Signed-off-by: JingYi Hou <[email protected]>

Applied and queued up for -stable, thanks.