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| author | Hannes Frederic Sowa <hannes@stressinduktion.org> | 2013-11-18 04:20:45 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-11-18 15:12:03 -0500 |
| commit | bceaa90240b6019ed73b49965eac7d167610be69 (patch) | |
| tree | f68c10948efff147a7b987369f1e720ad76f411b /net/l2tp/l2tp_ip.c | |
| parent | bcd081a3aef1f7f3786067ae8dd26aaa1cf85153 (diff) | |
| download | lwn-bceaa90240b6019ed73b49965eac7d167610be69.tar.gz lwn-bceaa90240b6019ed73b49965eac7d167610be69.zip | |
inet: prevent leakage of uninitialized memory to user in recv syscalls
Only update *addr_len when we actually fill in sockaddr, otherwise we
can return uninitialized memory from the stack to the caller in the
recvfrom, recvmmsg and recvmsg syscalls. Drop the the (addr_len == NULL)
checks because we only get called with a valid addr_len pointer either
from sock_common_recvmsg or inet_recvmsg.
If a blocking read waits on a socket which is concurrently shut down we
now return zero and set msg_msgnamelen to 0.
Reported-by: mpb <mpb.mail@gmail.com>
Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/l2tp/l2tp_ip.c')
| -rw-r--r-- | net/l2tp/l2tp_ip.c | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c index 571db8dd2292..da1a1cee1a08 100644 --- a/net/l2tp/l2tp_ip.c +++ b/net/l2tp/l2tp_ip.c @@ -518,9 +518,6 @@ static int l2tp_ip_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *m if (flags & MSG_OOB) goto out; - if (addr_len) - *addr_len = sizeof(*sin); - skb = skb_recv_datagram(sk, flags, noblock, &err); if (!skb) goto out; @@ -543,6 +540,7 @@ static int l2tp_ip_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *m sin->sin_addr.s_addr = ip_hdr(skb)->saddr; sin->sin_port = 0; memset(&sin->sin_zero, 0, sizeof(sin->sin_zero)); + *addr_len = sizeof(*sin); } if (inet->cmsg_flags) ip_cmsg_recv(msg, skb); |