netdev - [PATCH] Fix memory overwriting issue when copy an address to user space

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Message-ID: <CAEQHRfAC9me4hGA+=+wcOpx+TAzqS723-kr_Y_Ej8dnWHp2fTw@mail.gmail.com>
Date:   Mon, 20 Jul 2020 04:34:58 +0000
From:   lebon zhou <lebon.zhou@...il.com>
To:     davem@...emloft.net, kuba@...nel.org
Cc:     linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH] Fix memory overwriting issue when copy an address to user space

When application provided buffer size less than sockaddr_storage, then
kernel will overwrite some memory area which may cause memory corruption,
e.g.: in recvmsg case, let msg_name=malloc(8) and msg_namelen=8, then
usually application can call recvmsg successful but actually application
memory get corrupted.

Fix to return EINVAL when application buffer size less than
sockaddr_storage.

Signed-off-by: lebon.zhou <lebon.zhou@...il.com>
---
 net/socket.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/socket.c b/net/socket.c
index 976426d03f09..dc32b1b899df 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -229,7 +229,7 @@ static int move_addr_to_user(struct
sockaddr_storage *kaddr, int klen,
         return err;
     if (len > klen)
         len = klen;
-    if (len < 0)
+    if (len < 0 || len < klen)
         return -EINVAL;
     if (len) {
         if (audit_sockaddr(klen, kaddr))
--
2.22.0