Linux Kernel 3.12.3 inet uninitialized memory to user in recv syscalls

2014.01.09
Credit: mpb
Risk: Medium
Local: No
Remote: Yes
CWE: CWE-20


CVSS Base Score: 4.9/10
Impact Subscore: 6.9/10
Exploitability Subscore: 3.9/10
Exploit range: Local
Attack complexity: Low
Authentication: No required
Confidentiality impact: Complete
Integrity impact: None
Availability impact: None

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 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 9afbdb1..aacefa0 100644 --- a/net/ipv4/ping.c +++ b/net/ipv4/ping.c @@ -830,8 +830,6 @@ 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; @@ -841,13 +839,6 @@ 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); @@ -877,11 +868,13 @@ 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); @@ -890,17 +883,19 @@ 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 41e1d28..5cb8ddb 100644 --- a/net/ipv4/raw.c +++ b/net/ipv4/raw.c @@ -696,9 +696,6 @@ 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; @@ -726,6 +723,7 @@ 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 89909dd..998431c 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1235,12 +1235,6 @@ 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); @@ -1302,6 +1296,7 @@ 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 3c00842..e24ff1d 100644 --- a/net/ipv6/raw.c +++ b/net/ipv6/raw.c @@ -465,9 +465,6 @@ 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); @@ -506,6 +503,7 @@ 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 f3893e8..81eb8cf 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -392,9 +392,6 @@ 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); @@ -480,7 +477,7 @@ 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);

References:

https://github.com/torvalds/linux/commit/bceaa90240b6019ed73b49965eac7d167610be69
https://bugzilla.redhat.com/show_bug.cgi?id=1035875
http://www.openwall.com/lists/oss-security/2013/11/28/13
http://www.kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.12.4
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=bceaa90240b6019ed73b49965eac7d167610be69


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