| Message ID | 20190613104457.GA6296@hjy-HP-Notebook |
|---|---|
| State | Changes Requested |
| Delegated to: | David Miller |
| Headers | show |
| Series | fix double-fetch bug in sock_getsockopt() | expand |
From: JingYi Hou <houjingyi647@gmail.com> Date: Thu, 13 Jun 2019 18:44:57 +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 without check. > > if a malicious user can change it between two fetches may cause security > problems or unexpected behaivor. > > To fix this, we need to recheck it in the second fetch. > > Signed-off-by: JingYi Hou <houjingyi647@gmail.com> THere is no reason to fetch len a second time, so please just remove the get_user() call here instead. Also, please format your Subject line properly with appropriate subsystem prefixes etc.
diff --git a/net/core/sock.c b/net/core/sock.c index 2b3701958486..577780c935ee 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1479,6 +1479,8 @@ int sock_getsockopt(struct socket *sock, int level, int optname, if (get_user(len, optlen)) return -EFAULT; + if (len < 0) + return -EINVAL; sk_get_meminfo(sk, meminfo);
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 without check. if a malicious user can change it between two fetches may cause security problems or unexpected behaivor. To fix this, we need to recheck it in the second fetch. Signed-off-by: JingYi Hou <houjingyi647@gmail.com> --- net/core/sock.c | 2 ++ 1 file changed, 2 insertions(+)