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    Subject[PATCH 3.11 021/208] inet: prevent leakage of uninitialized memory to user in recv syscalls
    Date
    3.11.10.2 -stable review patch.  If anyone has any objections, please let me know.

    ------------------

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

    commit bceaa90240b6019ed73b49965eac7d167610be69 upstream.

    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: Luis Henriques <luis.henriques@canonical.com>
    ---
    net/ieee802154/dgram.c | 3 +--
    net/ipv4/ping.c | 19 +++++++------------
    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 ++++-----
    8 files changed, 17 insertions(+), 38 deletions(-)

    diff --git a/net/ieee802154/dgram.c b/net/ieee802154/dgram.c
    index 581a595..1865fdf 100644
    --- a/net/ieee802154/dgram.c
    +++ b/net/ieee802154/dgram.c
    @@ -315,9 +315,8 @@ static int dgram_recvmsg(struct kiocb *iocb, struct sock *sk,
    if (saddr) {
    saddr->family = AF_IEEE802154;
    saddr->addr = mac_cb(skb)->sa;
    - }
    - if (addr_len)
    *addr_len = sizeof(*saddr);
    + }

    if (flags & MSG_TRUNC)
    copied = skb->len;
    diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
    index 746427c..8bdf040 100644
    --- a/net/ipv4/ping.c
    +++ b/net/ipv4/ping.c
    @@ -827,8 +827,6 @@ int ping_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
    {
    struct inet_sock *isk = inet_sk(sk);
    int family = sk->sk_family;
    - struct sockaddr_in *sin;
    - struct sockaddr_in6 *sin6;
    struct sk_buff *skb;
    int copied, err;

    @@ -838,13 +836,6 @@ int ping_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
    if (flags & MSG_OOB)
    goto out;

    - if (addr_len) {
    - if (family == AF_INET)
    - *addr_len = sizeof(*sin);
    - else if (family == AF_INET6 && addr_len)
    - *addr_len = sizeof(*sin6);
    - }
    -
    if (flags & MSG_ERRQUEUE) {
    if (family == AF_INET) {
    return ip_recv_error(sk, msg, len);
    @@ -874,11 +865,13 @@ int ping_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,

    /* Copy the address and add cmsg data. */
    if (family == AF_INET) {
    - sin = (struct sockaddr_in *) 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);
    @@ -887,17 +880,19 @@ int ping_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
    } else if (family == AF_INET6) {
    struct ipv6_pinfo *np = inet6_sk(sk);
    struct ipv6hdr *ip6 = ipv6_hdr(skb);
    - sin6 = (struct sockaddr_in6 *) msg->msg_name;
    + struct sockaddr_in6 *sin6 =
    + (struct sockaddr_in6 *)msg->msg_name;
    +
    sin6->sin6_family = AF_INET6;
    sin6->sin6_port = 0;
    sin6->sin6_addr = ip6->saddr;
    -
    sin6->sin6_flowinfo = 0;
    if (np->sndflow)
    sin6->sin6_flowinfo = ip6_flowinfo(ip6);

    sin6->sin6_scope_id = ipv6_iface_scope_id(&sin6->sin6_addr,
    IP6CB(skb)->iif);
    + *addr_len = sizeof(*sin6);

    if (inet6_sk(sk)->rxopt.all)
    pingv6_ops.ip6_datagram_recv_ctl(sk, msg, skb);
    diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
    index 6fb2337..448e5a7 100644
    --- a/net/ipv4/raw.c
    +++ b/net/ipv4/raw.c
    @@ -692,9 +692,6 @@ 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;
    @@ -722,6 +719,7 @@ 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 766e6ba..c69955f 100644
    --- a/net/ipv4/udp.c
    +++ b/net/ipv4/udp.c
    @@ -1208,12 +1208,6 @@ 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);

    @@ -1275,6 +1269,7 @@ 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 cdaed47..8aa1b31 100644
    --- a/net/ipv6/raw.c
    +++ b/net/ipv6/raw.c
    @@ -459,9 +459,6 @@ 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);

    @@ -500,6 +497,7 @@ static int rawv6_recvmsg(struct kiocb *iocb, struct sock *sk,
    sin6->sin6_flowinfo = 0;
    sin6->sin6_scope_id = ipv6_iface_scope_id(&sin6->sin6_addr,
    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 f405815..a483286 100644
    --- a/net/ipv6/udp.c
    +++ b/net/ipv6/udp.c
    @@ -374,9 +374,6 @@ 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);

    @@ -462,7 +459,7 @@ try_again:
    ipv6_iface_scope_id(&sin6->sin6_addr,
    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 571db8d..da1a1ce 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);
    diff --git a/net/phonet/datagram.c b/net/phonet/datagram.c
    index 12c30f3..38946b2 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);
    --
    1.8.3.2


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