[PATCH 3.2 158/185] inet: prevent leakage of uninitialized memory to user in recv syscalls

Ben Hutchings
2013-12-29T02:10:29Z

From: Hannes Frederic Sowa <hannes@stressinduktion.org>

[ Upstream commit bceaa90240b6019ed73b49965eac7d167610be69 ]

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/ipv4/ping.c | 9 ++++-----
net/ipv4/raw.c | 4 +---
net/ipv4/udp.c | 7 +------
net/ipv6/raw.c | 4 +---
net/ipv6/udp.c | 5 +----
net/l2tp/l2tp_ip.c | 4 +---
net/phonet/datagram.c | 9 ++++-----
7 files changed, 13 insertions(+), 29 deletions(-)

diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index 294a380..41fea2d 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -623,7 +623,6 @@ static int ping_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
size_t len, int noblock, int flags, int *addr_len)
{
struct inet_sock *isk = inet_sk(sk);
- struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
struct sk_buff *skb;
int copied, err;

@@ -632,9 +631,6 @@ static int ping_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
if (flags & MSG_OOB)
goto out;

- if (addr_len)
- *addr_len = sizeof(*sin);
-
if (flags & MSG_ERRQUEUE)
return ip_recv_error(sk, msg, len);

@@ -656,11 +652,14 @@ static int ping_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
sock_recv_timestamp(msg, sk, skb);

/* Copy the address. */
- if (sin) {
+ if (msg->msg_name) {
+ struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
+
sin->sin_family = AF_INET;
sin->sin_port = 0 /* skb->h.uh->source */;
sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
+ *addr_len = sizeof(*sin);
}
if (isk->cmsg_flags)
ip_cmsg_recv(msg, skb);
diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 2815014..c676d07 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -686,9 +686,6 @@ static int raw_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
if (flags & MSG_OOB)
goto out;

- if (addr_len)
- *addr_len = sizeof(*sin);
-
if (flags & MSG_ERRQUEUE) {
err = ip_recv_error(sk, msg, len);
goto out;
@@ -716,6 +713,7 @@ static int raw_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
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);
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 5decc93..107ab5c 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1171,12 +1171,6 @@ int udp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
int is_udplite = IS_UDPLITE(sk);
bool slow;

- /*
- * Check any passed addresses
- */
- if (addr_len)
- *addr_len = sizeof(*sin);
-
if (flags & MSG_ERRQUEUE)
return ip_recv_error(sk, msg, len);

@@ -1231,6 +1225,7 @@ try_again:
sin->sin_port = udp_hdr(skb)->source;
sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
+ *addr_len = sizeof(*sin);
}
if (inet->cmsg_flags)
ip_cmsg_recv(msg, skb);
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index 6e6c2c4..3278f27 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -456,9 +456,6 @@ static int rawv6_recvmsg(struct kiocb *iocb, struct sock *sk,
if (flags & MSG_OOB)
return -EOPNOTSUPP;

- if (addr_len)
- *addr_len=sizeof(*sin6);
-
if (flags & MSG_ERRQUEUE)
return ipv6_recv_error(sk, msg, len);

@@ -498,6 +495,7 @@ static int rawv6_recvmsg(struct kiocb *iocb, struct sock *sk,
sin6->sin6_scope_id = 0;
if (ipv6_addr_type(&sin6->sin6_addr) & IPV6_ADDR_LINKLOCAL)
sin6->sin6_scope_id = IP6CB(skb)->iif;
+ *addr_len = sizeof(*sin6);
}

sock_recv_ts_and_drops(msg, sk, skb);
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index f9e496b..391329e 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -347,9 +347,6 @@ int udpv6_recvmsg(struct kiocb *iocb, struct sock *sk,
int is_udp4;
bool slow;

- if (addr_len)
- *addr_len=sizeof(struct sockaddr_in6);
-
if (flags & MSG_ERRQUEUE)
return ipv6_recv_error(sk, msg, len);

@@ -423,7 +420,7 @@ try_again:
if (ipv6_addr_type(&sin6->sin6_addr) & IPV6_ADDR_LINKLOCAL)
sin6->sin6_scope_id = IP6CB(skb)->iif;
}
-
+ *addr_len = sizeof(*sin6);
}
if (is_udp4) {
if (inet->cmsg_flags)
diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
index 6c7e609..334a93d 100644
--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -568,9 +568,6 @@ 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;
@@ -593,6 +590,7 @@ 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);
diff --git a/net/phonet/datagram.c b/net/phonet/datagram.c
index bf35b4e..b25f2d3 100644
--- a/net/phonet/datagram.c
+++ b/net/phonet/datagram.c
@@ -139,9 +139,6 @@ static int pn_recvmsg(struct kiocb *iocb, struct sock *sk,
MSG_CMSG_COMPAT))
goto out_nofree;

- if (addr_len)
- *addr_len = sizeof(sa);
-
skb = skb_recv_datagram(sk, flags, noblock, &rval);
if (skb == NULL)
goto out_nofree;
@@ -162,8 +159,10 @@ static int pn_recvmsg(struct kiocb *iocb, struct sock *sk,

rval = (flags & MSG_TRUNC) ? skb->len : copylen;

- if (msg->msg_name != NULL)
- memcpy(msg->msg_name, &sa, sizeof(struct sockaddr_pn));
+ if (msg->msg_name != NULL) {
+ memcpy(msg->msg_name, &sa, sizeof(sa));
+ *addr_len = sizeof(sa);
+ }

out:
skb_free_datagram(sk, skb);