From 79462ad02e861803b3840cc782248c7359451cd9 Mon Sep 17 00:00:00 2001 From: Hannes Frederic Sowa Date: Mon, 14 Dec 2015 22:03:39 +0100 Subject: net: add validation for the socket syscall protocol argument MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 郭永刚 reported that one could simply crash the kernel as root by using a simple program: int socket_fd; struct sockaddr_in addr; addr.sin_port = 0; addr.sin_addr.s_addr = INADDR_ANY; addr.sin_family = 10; socket_fd = socket(10,3,0x40000000); connect(socket_fd , &addr,16); AF_INET, AF_INET6 sockets actually only support 8-bit protocol identifiers. inet_sock's skc_protocol field thus is sized accordingly, thus larger protocol identifiers simply cut off the higher bits and store a zero in the protocol fields. This could lead to e.g. NULL function pointer because as a result of the cut off inet_num is zero and we call down to inet_autobind, which is NULL for raw sockets. kernel: Call Trace: kernel: [] ? inet_autobind+0x2e/0x70 kernel: [] inet_dgram_connect+0x54/0x80 kernel: [] SYSC_connect+0xd9/0x110 kernel: [] ? ptrace_notify+0x5b/0x80 kernel: [] ? syscall_trace_enter_phase2+0x108/0x200 kernel: [] SyS_connect+0xe/0x10 kernel: [] tracesys_phase2+0x84/0x89 I found no particular commit which introduced this problem. CVE: CVE-2015-8543 Cc: Cong Wang Reported-by: 郭永刚 Signed-off-by: Hannes Frederic Sowa Signed-off-by: David S. Miller --- net/ipv6/af_inet6.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'net/ipv6/af_inet6.c') diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c index 8ec0df75f1c4..9f5137cd604e 100644 --- a/net/ipv6/af_inet6.c +++ b/net/ipv6/af_inet6.c @@ -109,6 +109,9 @@ static int inet6_create(struct net *net, struct socket *sock, int protocol, int try_loading_module = 0; int err; + if (protocol < 0 || protocol >= IPPROTO_MAX) + return -EINVAL; + /* Look for the requested type/protocol pair. */ lookup_protocol: err = -ESOCKTNOSUPPORT; -- cgit