From 09279e615c81ce55e04835970601ae286e3facbe Mon Sep 17 00:00:00 2001 From: Xin Long Date: Sun, 31 Mar 2019 16:58:15 +0800 Subject: [PATCH] sctp: initialize _pad of sockaddr_in before copying to user memory Syzbot report a kernel-infoleak: BUG: KMSAN: kernel-infoleak in _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32 Call Trace: _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32 copy_to_user include/linux/uaccess.h:174 [inline] sctp_getsockopt_peer_addrs net/sctp/socket.c:5911 [inline] sctp_getsockopt+0x1668e/0x17f70 net/sctp/socket.c:7562 ... Uninit was stored to memory at: sctp_transport_init net/sctp/transport.c:61 [inline] sctp_transport_new+0x16d/0x9a0 net/sctp/transport.c:115 sctp_assoc_add_peer+0x532/0x1f70 net/sctp/associola.c:637 sctp_process_param net/sctp/sm_make_chunk.c:2548 [inline] sctp_process_init+0x1a1b/0x3ed0 net/sctp/sm_make_chunk.c:2361 ... Bytes 8-15 of 16 are uninitialized It was caused by that th _pad field (the 8-15 bytes) of a v4 addr (saved in struct sockaddr_in) wasn't initialized, but directly copied to user memory in sctp_getsockopt_peer_addrs(). So fix it by calling memset(addr->v4.sin_zero, 0, 8) to initialize _pad of sockaddr_in before copying it to user memory in sctp_v4_addr_to_user(), as sctp_v6_addr_to_user() does. Reported-by: syzbot+86b5c7c236a22616a72f@syzkaller.appspotmail.com Signed-off-by: Xin Long Tested-by: Alexander Potapenko Acked-by: Neil Horman Signed-off-by: David S. Miller --- net/sctp/protocol.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c index 6abc8b2..951afde 100644 --- a/net/sctp/protocol.c +++ b/net/sctp/protocol.c @@ -600,6 +600,7 @@ out: static int sctp_v4_addr_to_user(struct sctp_sock *sp, union sctp_addr *addr) { /* No address mapping for V4 sockets */ + memset(addr->v4.sin_zero, 0, sizeof(addr->v4.sin_zero)); return sizeof(struct sockaddr_in); } -- 2.7.4