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Date: Thu, 13 Jun 2019 18:44:57 +0800 From: JingYi Hou <houjingyi647@...il.com> To: davem@...emloft.net Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org Subject: [PATCH] fix double-fetch bug 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 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@...il.com> --- net/core/sock.c | 2 ++ 1 file changed, 2 insertions(+) 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); -- 2.20.1
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