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llc: Fix missing msg_namelen update in llc_ui_recvmsg()

For stream sockets the code misses to update the msg_namelen member
to 0 and therefore makes net/socket.c leak the local, uninitialized
sockaddr_storage variable to userland -- 128 bytes of kernel stack
memory. The msg_namelen update is also missing for datagram sockets
in case the socket is shutting down during receive.

Fix both issues by setting msg_namelen to 0 early. It will be
updated later if we're going to fill the msg_name member.

Cc: Arnaldo Carvalho de Melo <>
Signed-off-by: Mathias Krause <>
Signed-off-by: David S. Miller <>
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commit c77a4b9cffb6215a15196ec499490d116dfad181 1 parent b860d3c
@minipli minipli authored davem330 committed
Showing with 2 additions and 0 deletions.
  1. +2 −0  net/llc/af_llc.c
2  net/llc/af_llc.c
@@ -720,6 +720,8 @@ static int llc_ui_recvmsg(struct kiocb *iocb, struct socket *sock,
int target; /* Read at least this many bytes */
long timeo;
+ msg->msg_namelen = 0;
copied = -ENOTCONN;
if (unlikely(sk->sk_type == SOCK_STREAM && sk->sk_state == TCP_LISTEN))
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