tcp: fix potential double free issue for fastopen_req
authorWei Wang <weiwan@google.com>
Wed, 1 Mar 2017 21:29:48 +0000 (13:29 -0800)
committerDavid S. Miller <davem@davemloft.net>
Thu, 2 Mar 2017 22:05:41 +0000 (14:05 -0800)
commit7db92362d2fee5887f6b0c41653b8c9f8f5d6020
tree4d1b45575d0b490061671c4dddaa32f795013e59
parent94352d45092c23874532221b4d1e4721df9d63df
tcp: fix potential double free issue for fastopen_req

tp->fastopen_req could potentially be double freed if a malicious
user does the following:
1. Enable TCP_FASTOPEN_CONNECT sockopt and do a connect() on the socket.
2. Call connect() with AF_UNSPEC to disconnect the socket.
3. Make this socket a listening socket by calling listen().
4. Accept incoming connections and generate child sockets. All child
   sockets will get a copy of the pointer of fastopen_req.
5. Call close() on all sockets. fastopen_req will get freed multiple
   times.

Fixes: 19f6d3f3c842 ("net/tcp-fastopen: Add new API support")
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/ipv4/tcp.c