Bug 205605

Info
===

Bug: Memory leak in ip_mc_source (Networking / IPv4)
Kernel: 4.19.83 (other version probably also affected)
Tested on: Debian 9 x86_64
Report date: 2019-11-20

Report
===

There is a memory leak in the function "ip_mc_source" located in "net/ipv4/igmp.c"

Details:

Syzkaller hit 'memory leak in ip_mc_source' bug.
BUG: memory leak
unreferenced object 0xffff888027e796c0 (size 64):
  comm "syz-executor300", pid 2091, jiffies 4294798836 (age 14.231s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 ac 1e 00 01 00 00 00 00  ................
    00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00  ................
  backtrace:
    [<000000006f09add3>] ip_mc_source+0xabb/0x1140 net/ipv4/igmp.c:2412
    [<00000000048dc00d>] do_ip_setsockopt.isra.14+0x1860/0x3c60 net/ipv4/ip_sockglue.c:996
    [<0000000087e46a3b>] ip_setsockopt+0x40/0xf0 net/ipv4/ip_sockglue.c:1246
    [<00000000a3cc60d4>] raw_setsockopt+0xd9/0x100 net/ipv4/raw.c:861
    [<000000001fc763e1>] __sys_setsockopt+0x18e/0x370 net/socket.c:1901
    [<00000000ea3dd357>] __do_sys_setsockopt net/socket.c:1912 [inline]
    [<00000000ea3dd357>] __se_sys_setsockopt net/socket.c:1909 [inline]
    [<00000000ea3dd357>] __x64_sys_setsockopt+0xba/0x150 net/socket.c:1909
    [<00000000357c1bdf>] do_syscall_64+0x167/0x6c0 arch/x86/entry/common.c:293
    [<000000000a84791e>] entry_SYSCALL_64_after_hwframe+0x49/0xbe
    [<000000006f276b76>] 0xffffffffffffffff


Reproducer (Syzkaller)
===

# {Threaded:false Collide:false Repeat:false RepeatTimes:0 Procs:1 Sandbox:none Fault:false FaultCall:-1 FaultNth:0 Leak:true EnableTun:false EnableNetDev:true EnableNetReset:false EnableCgroups:false EnableBinfmtMisc:false EnableCloseFds:false EnableKCSAN:false UseTmpDir:true HandleSegv:false Repro:false Trace:false}
r0 = socket$nl_xfrm(0x10, 0x3, 0x6)
r1 = socket$inet_icmp_raw(0x2, 0x3, 0x1)
setsockopt$inet_mreqsrc(r1, 0x0, 0x27, &(0x7f0000000000)={@multicast2, @dev={0xac, 0x14, 0x14, 0x25}, @initdev={0xac, 0x1e, 0x0, 0x0}}, 0xc)
ioctl$sock_ifreq(r0, 0x8922, &(0x7f0000000240)={'lo\x00', @ifru_flags})


Reproducer (C code)
===

#define _GNU_SOURCE 

#include <arpa/inet.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <netinet/in.h>
#include <sched.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/prctl.h>
#include <sys/resource.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

#include <linux/capability.h>
#include <linux/if_addr.h>
#include <linux/if_ether.h>
#include <linux/if_link.h>
#include <linux/if_tun.h>
#include <linux/in6.h>
#include <linux/ip.h>
#include <linux/neighbour.h>
#include <linux/net.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <linux/tcp.h>
#include <linux/veth.h>

unsigned long long procid;

static uint64_t current_time_ms(void)
{
	struct timespec ts;
	if (clock_gettime(CLOCK_MONOTONIC, &ts))
	exit(1);
	return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
}

static void use_temporary_dir(void)
{
	char tmpdir_template[] = "./syzkaller.XXXXXX";
	char* tmpdir = mkdtemp(tmpdir_template);
	if (!tmpdir)
	exit(1);
	if (chmod(tmpdir, 0777))
	exit(1);
	if (chdir(tmpdir))
	exit(1);
}

static bool write_file(const char* file, const char* what, ...)
{
	char buf[1024];
	va_list args;
	va_start(args, what);
	vsnprintf(buf, sizeof(buf), what, args);
	va_end(args);
	buf[sizeof(buf) - 1] = 0;
	int len = strlen(buf);
	int fd = open(file, O_WRONLY | O_CLOEXEC);
	if (fd == -1)
		return false;
	if (write(fd, buf, len) != len) {
		int err = errno;
		close(fd);
		errno = err;
		return false;
	}
	close(fd);
	return true;
}

static struct {
	char* pos;
	int nesting;
	struct nlattr* nested[8];
	char buf[1024];
} nlmsg;

static void netlink_init(int typ, int flags, const void* data, int size)
{
	memset(&nlmsg, 0, sizeof(nlmsg));
	struct nlmsghdr* hdr = (struct nlmsghdr*)nlmsg.buf;
	hdr->nlmsg_type = typ;
	hdr->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | flags;
	memcpy(hdr + 1, data, size);
	nlmsg.pos = (char*)(hdr + 1) + NLMSG_ALIGN(size);
}

static void netlink_attr(int typ, const void* data, int size)
{
	struct nlattr* attr = (struct nlattr*)nlmsg.pos;
	attr->nla_len = sizeof(*attr) + size;
	attr->nla_type = typ;
	memcpy(attr + 1, data, size);
	nlmsg.pos += NLMSG_ALIGN(attr->nla_len);
}

static void netlink_nest(int typ)
{
	struct nlattr* attr = (struct nlattr*)nlmsg.pos;
	attr->nla_type = typ;
	nlmsg.pos += sizeof(*attr);
	nlmsg.nested[nlmsg.nesting++] = attr;
}

static void netlink_done(void)
{
	struct nlattr* attr = nlmsg.nested[--nlmsg.nesting];
	attr->nla_len = nlmsg.pos - (char*)attr;
}

static int netlink_send(int sock)
{
	if (nlmsg.pos > nlmsg.buf + sizeof(nlmsg.buf) || nlmsg.nesting)
	exit(1);
	struct nlmsghdr* hdr = (struct nlmsghdr*)nlmsg.buf;
	hdr->nlmsg_len = nlmsg.pos - nlmsg.buf;
	struct sockaddr_nl addr;
	memset(&addr, 0, sizeof(addr));
	addr.nl_family = AF_NETLINK;
	unsigned n = sendto(sock, nlmsg.buf, hdr->nlmsg_len, 0, (struct sockaddr*)&addr, sizeof(addr));
	if (n != hdr->nlmsg_len)
	exit(1);
	n = recv(sock, nlmsg.buf, sizeof(nlmsg.buf), 0);
	if (n < sizeof(struct nlmsghdr) + sizeof(struct nlmsgerr))
	exit(1);
	if (hdr->nlmsg_type != NLMSG_ERROR)
	exit(1);
	return -((struct nlmsgerr*)(hdr + 1))->error;
}

static void netlink_add_device_impl(const char* type, const char* name)
{
	struct ifinfomsg hdr;
	memset(&hdr, 0, sizeof(hdr));
	netlink_init(RTM_NEWLINK, NLM_F_EXCL | NLM_F_CREATE, &hdr, sizeof(hdr));
	if (name)
		netlink_attr(IFLA_IFNAME, name, strlen(name));
	netlink_nest(IFLA_LINKINFO);
	netlink_attr(IFLA_INFO_KIND, type, strlen(type));
}

static void netlink_add_device(int sock, const char* type, const char* name)
{
	netlink_add_device_impl(type, name);
	netlink_done();
	int err = netlink_send(sock);
	(void)err;
}

static void netlink_add_veth(int sock, const char* name, const char* peer)
{
	netlink_add_device_impl("veth", name);
	netlink_nest(IFLA_INFO_DATA);
	netlink_nest(VETH_INFO_PEER);
	nlmsg.pos += sizeof(struct ifinfomsg);
	netlink_attr(IFLA_IFNAME, peer, strlen(peer));
	netlink_done();
	netlink_done();
	netlink_done();
	int err = netlink_send(sock);
	(void)err;
}

static void netlink_add_hsr(int sock, const char* name, const char* slave1, const char* slave2)
{
	netlink_add_device_impl("hsr", name);
	netlink_nest(IFLA_INFO_DATA);
	int ifindex1 = if_nametoindex(slave1);
	netlink_attr(IFLA_HSR_SLAVE1, &ifindex1, sizeof(ifindex1));
	int ifindex2 = if_nametoindex(slave2);
	netlink_attr(IFLA_HSR_SLAVE2, &ifindex2, sizeof(ifindex2));
	netlink_done();
	netlink_done();
	int err = netlink_send(sock);
	(void)err;
}

static void netlink_device_change(int sock, const char* name, bool up,
				  const char* master, const void* mac, int macsize)
{
	struct ifinfomsg hdr;
	memset(&hdr, 0, sizeof(hdr));
	if (up)
		hdr.ifi_flags = hdr.ifi_change = IFF_UP;
	netlink_init(RTM_NEWLINK, 0, &hdr, sizeof(hdr));
	netlink_attr(IFLA_IFNAME, name, strlen(name));
	if (master) {
		int ifindex = if_nametoindex(master);
		netlink_attr(IFLA_MASTER, &ifindex, sizeof(ifindex));
	}
	if (macsize)
		netlink_attr(IFLA_ADDRESS, mac, macsize);
	int err = netlink_send(sock);
	(void)err;
}

static int netlink_add_addr(int sock, const char* dev, const void* addr, int addrsize)
{
	struct ifaddrmsg hdr;
	memset(&hdr, 0, sizeof(hdr));
	hdr.ifa_family = addrsize == 4 ? AF_INET : AF_INET6;
	hdr.ifa_prefixlen = addrsize == 4 ? 24 : 120;
	hdr.ifa_scope = RT_SCOPE_UNIVERSE;
	hdr.ifa_index = if_nametoindex(dev);
	netlink_init(RTM_NEWADDR, NLM_F_CREATE | NLM_F_REPLACE, &hdr, sizeof(hdr));
	netlink_attr(IFA_LOCAL, addr, addrsize);
	netlink_attr(IFA_ADDRESS, addr, addrsize);
	return netlink_send(sock);
}

static void netlink_add_addr4(int sock, const char* dev, const char* addr)
{
	struct in_addr in_addr;
	inet_pton(AF_INET, addr, &in_addr);
	int err = netlink_add_addr(sock, dev, &in_addr, sizeof(in_addr));
	(void)err;
}

static void netlink_add_addr6(int sock, const char* dev, const char* addr)
{
	struct in6_addr in6_addr;
	inet_pton(AF_INET6, addr, &in6_addr);
	int err = netlink_add_addr(sock, dev, &in6_addr, sizeof(in6_addr));
	(void)err;
}

#define DEV_IPV4 "172.20.20.%d"
#define DEV_IPV6 "fe80::%02x"
#define DEV_MAC 0x00aaaaaaaaaa

static void netdevsim_add(unsigned int addr, unsigned int port_count)
{
	char buf[16];
	sprintf(buf, "%u %u", addr, port_count);
	write_file("/sys/bus/netdevsim/new_device", buf);
}
static void initialize_netdevices(void)
{
	char netdevsim[16];
	sprintf(netdevsim, "netdevsim%d", (int)procid);
	struct {
		const char* type;
		const char* dev;
	} devtypes[] = {
	    {"ip6gretap", "ip6gretap0"},
	    {"bridge", "bridge0"},
	    {"vcan", "vcan0"},
	    {"bond", "bond0"},
	    {"team", "team0"},
	    {"dummy", "dummy0"},
	    {"nlmon", "nlmon0"},
	    {"caif", "caif0"},
	    {"batadv", "batadv0"},
	    {"vxcan", "vxcan1"},
	    {"netdevsim", netdevsim},
	    {"veth", 0},
	};
	const char* devmasters[] = {"bridge", "bond", "team"};
	struct {
		const char* name;
		int macsize;
		bool noipv6;
	} devices[] = {
	    {"lo", ETH_ALEN},
	    {"sit0", 0},
	    {"bridge0", ETH_ALEN},
	    {"vcan0", 0, true},
	    {"tunl0", 0},
	    {"gre0", 0},
	    {"gretap0", ETH_ALEN},
	    {"ip_vti0", 0},
	    {"ip6_vti0", 0},
	    {"ip6tnl0", 0},
	    {"ip6gre0", 0},
	    {"ip6gretap0", ETH_ALEN},
	    {"erspan0", ETH_ALEN},
	    {"bond0", ETH_ALEN},
	    {"veth0", ETH_ALEN},
	    {"veth1", ETH_ALEN},
	    {"team0", ETH_ALEN},
	    {"veth0_to_bridge", ETH_ALEN},
	    {"veth1_to_bridge", ETH_ALEN},
	    {"veth0_to_bond", ETH_ALEN},
	    {"veth1_to_bond", ETH_ALEN},
	    {"veth0_to_team", ETH_ALEN},
	    {"veth1_to_team", ETH_ALEN},
	    {"veth0_to_hsr", ETH_ALEN},
	    {"veth1_to_hsr", ETH_ALEN},
	    {"hsr0", 0},
	    {"dummy0", ETH_ALEN},
	    {"nlmon0", 0},
	    {"vxcan1", 0, true},
	    {"caif0", ETH_ALEN},
	    {"batadv0", ETH_ALEN},
	    {netdevsim, ETH_ALEN},
	};
	int sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
	if (sock == -1)
	exit(1);
	unsigned i;
	for (i = 0; i < sizeof(devtypes) / sizeof(devtypes[0]); i++)
		netlink_add_device(sock, devtypes[i].type, devtypes[i].dev);
	for (i = 0; i < sizeof(devmasters) / (sizeof(devmasters[0])); i++) {
		char master[32], slave0[32], veth0[32], slave1[32], veth1[32];
		sprintf(slave0, "%s_slave_0", devmasters[i]);
		sprintf(veth0, "veth0_to_%s", devmasters[i]);
		netlink_add_veth(sock, slave0, veth0);
		sprintf(slave1, "%s_slave_1", devmasters[i]);
		sprintf(veth1, "veth1_to_%s", devmasters[i]);
		netlink_add_veth(sock, slave1, veth1);
		sprintf(master, "%s0", devmasters[i]);
		netlink_device_change(sock, slave0, false, master, 0, 0);
		netlink_device_change(sock, slave1, false, master, 0, 0);
	}
	netlink_device_change(sock, "bridge_slave_0", true, 0, 0, 0);
	netlink_device_change(sock, "bridge_slave_1", true, 0, 0, 0);
	netlink_add_veth(sock, "hsr_slave_0", "veth0_to_hsr");
	netlink_add_veth(sock, "hsr_slave_1", "veth1_to_hsr");
	netlink_add_hsr(sock, "hsr0", "hsr_slave_0", "hsr_slave_1");
	netlink_device_change(sock, "hsr_slave_0", true, 0, 0, 0);
	netlink_device_change(sock, "hsr_slave_1", true, 0, 0, 0);
	netdevsim_add((int)procid, 4);
	for (i = 0; i < sizeof(devices) / (sizeof(devices[0])); i++) {
		char addr[32];
		sprintf(addr, DEV_IPV4, i + 10);
		netlink_add_addr4(sock, devices[i].name, addr);
		if (!devices[i].noipv6) {
			sprintf(addr, DEV_IPV6, i + 10);
			netlink_add_addr6(sock, devices[i].name, addr);
		}
		uint64_t macaddr = DEV_MAC + ((i + 10ull) << 40);
		netlink_device_change(sock, devices[i].name, true, 0, &macaddr, devices[i].macsize);
	}
	close(sock);
}
static void initialize_netdevices_init(void)
{
	int sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
	if (sock == -1)
	exit(1);
	struct {
		const char* type;
		int macsize;
		bool noipv6;
		bool noup;
	} devtypes[] = {
	    {"nr", 7, true},
	    {"rose", 5, true, true},
	};
	unsigned i;
	for (i = 0; i < sizeof(devtypes) / sizeof(devtypes[0]); i++) {
		char dev[32], addr[32];
		sprintf(dev, "%s%d", devtypes[i].type, (int)procid);
		sprintf(addr, "172.30.%d.%d", i, (int)procid + 1);
		netlink_add_addr4(sock, dev, addr);
		if (!devtypes[i].noipv6) {
			sprintf(addr, "fe88::%02x:%02x", i, (int)procid + 1);
			netlink_add_addr6(sock, dev, addr);
		}
		int macsize = devtypes[i].macsize;
		uint64_t macaddr = 0xbbbbbb + ((unsigned long long)i << (8 * (macsize - 2))) +
				 (procid << (8 * (macsize - 1)));
		netlink_device_change(sock, dev, !devtypes[i].noup, 0, &macaddr, macsize);
	}
	close(sock);
}

static void setup_common()
{
	if (mount(0, "/sys/fs/fuse/connections", "fusectl", 0, 0)) {
	}
}

static void loop();

static void sandbox_common()
{
	prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
	setpgrp();
	setsid();
	struct rlimit rlim;
	rlim.rlim_cur = rlim.rlim_max = (200 << 20);
	setrlimit(RLIMIT_AS, &rlim);
	rlim.rlim_cur = rlim.rlim_max = 32 << 20;
	setrlimit(RLIMIT_MEMLOCK, &rlim);
	rlim.rlim_cur = rlim.rlim_max = 136 << 20;
	setrlimit(RLIMIT_FSIZE, &rlim);
	rlim.rlim_cur = rlim.rlim_max = 1 << 20;
	setrlimit(RLIMIT_STACK, &rlim);
	rlim.rlim_cur = rlim.rlim_max = 0;
	setrlimit(RLIMIT_CORE, &rlim);
	rlim.rlim_cur = rlim.rlim_max = 256;
	setrlimit(RLIMIT_NOFILE, &rlim);
	if (unshare(CLONE_NEWNS)) {
	}
	if (unshare(CLONE_NEWIPC)) {
	}
	if (unshare(0x02000000)) {
	}
	if (unshare(CLONE_NEWUTS)) {
	}
	if (unshare(CLONE_SYSVSEM)) {
	}
	typedef struct {
		const char* name;
		const char* value;
	} sysctl_t;
	static const sysctl_t sysctls[] = {
	    {"/proc/sys/kernel/shmmax", "16777216"},
	    {"/proc/sys/kernel/shmall", "536870912"},
	    {"/proc/sys/kernel/shmmni", "1024"},
	    {"/proc/sys/kernel/msgmax", "8192"},
	    {"/proc/sys/kernel/msgmni", "1024"},
	    {"/proc/sys/kernel/msgmnb", "1024"},
	    {"/proc/sys/kernel/sem", "1024 1048576 500 1024"},
	};
	unsigned i;
	for (i = 0; i < sizeof(sysctls) / sizeof(sysctls[0]); i++)
		write_file(sysctls[i].name, sysctls[i].value);
}

int wait_for_loop(int pid)
{
	if (pid < 0)
	exit(1);
	int status = 0;
	while (waitpid(-1, &status, __WALL) != pid) {
	}
	return WEXITSTATUS(status);
}

static void drop_caps(void)
{
	struct __user_cap_header_struct cap_hdr = {};
	struct __user_cap_data_struct cap_data[2] = {};
	cap_hdr.version = _LINUX_CAPABILITY_VERSION_3;
	cap_hdr.pid = getpid();
	if (syscall(SYS_capget, &cap_hdr, &cap_data))
	exit(1);
	const int drop = (1 << CAP_SYS_PTRACE) | (1 << CAP_SYS_NICE);
	cap_data[0].effective &= ~drop;
	cap_data[0].permitted &= ~drop;
	cap_data[0].inheritable &= ~drop;
	if (syscall(SYS_capset, &cap_hdr, &cap_data))
	exit(1);
}

static int do_sandbox_none(void)
{
	if (unshare(CLONE_NEWPID)) {
	}
	int pid = fork();
	if (pid != 0)
		return wait_for_loop(pid);
	setup_common();
	sandbox_common();
	drop_caps();
	initialize_netdevices_init();
	if (unshare(CLONE_NEWNET)) {
	}
	initialize_netdevices();
	loop();
	exit(1);
}

#define KMEMLEAK_FILE "/sys/kernel/debug/kmemleak"

static void setup_leak()
{
	if (!write_file(KMEMLEAK_FILE, "scan"))
	exit(1);
	sleep(5);
	if (!write_file(KMEMLEAK_FILE, "scan"))
	exit(1);
	if (!write_file(KMEMLEAK_FILE, "clear"))
	exit(1);
}

static void check_leaks(void)
{
	int fd = open(KMEMLEAK_FILE, O_RDWR);
	if (fd == -1)
	exit(1);
	uint64_t start = current_time_ms();
	if (write(fd, "scan", 4) != 4)
	exit(1);
	sleep(1);
	while (current_time_ms() - start < 4 * 1000)
		sleep(1);
	if (write(fd, "scan", 4) != 4)
	exit(1);
	static char buf[128 << 10];
	ssize_t n = read(fd, buf, sizeof(buf) - 1);
	if (n < 0)
	exit(1);
	int nleaks = 0;
	if (n != 0) {
		sleep(1);
		if (write(fd, "scan", 4) != 4)
	exit(1);
		if (lseek(fd, 0, SEEK_SET) < 0)
	exit(1);
		n = read(fd, buf, sizeof(buf) - 1);
		if (n < 0)
	exit(1);
		buf[n] = 0;
		char* pos = buf;
		char* end = buf + n;
		while (pos < end) {
			char* next = strstr(pos + 1, "unreferenced object");
			if (!next)
				next = end;
			char prev = *next;
			*next = 0;
			fprintf(stderr, "BUG: memory leak\n%s\n", pos);
			*next = prev;
			pos = next;
			nleaks++;
		}
	}
	if (write(fd, "clear", 5) != 5)
	exit(1);
	close(fd);
	if (nleaks)
		exit(1);
}

uint64_t r[2] = {0xffffffffffffffff, 0xffffffffffffffff};

void loop(void)
{
		intptr_t res = 0;
	res = syscall(__NR_socket, 0x10, 3, 6);
	if (res != -1)
		r[0] = res;
	res = syscall(__NR_socket, 2, 3, 1);
	if (res != -1)
		r[1] = res;
*(uint32_t*)0x20000000 = htobe32(0xe0000002);
*(uint8_t*)0x20000004 = 0xac;
*(uint8_t*)0x20000005 = 0x14;
*(uint8_t*)0x20000006 = 0x14;
*(uint8_t*)0x20000007 = 0x25;
*(uint8_t*)0x20000008 = 0xac;
*(uint8_t*)0x20000009 = 0x1e;
*(uint8_t*)0x2000000a = 0;
*(uint8_t*)0x2000000b = 1;
	syscall(__NR_setsockopt, r[1], 0, 0x27, 0x20000000, 0xc);
memcpy((void*)0x20000240, "lo\000\000\000\000\000\000\000\000\000\000\000\000\000\000", 16);
*(uint16_t*)0x20000250 = 0;
	syscall(__NR_ioctl, r[0], 0x8922, 0x20000240);

}
int main(void)
{
		syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0);
	setup_leak();
			use_temporary_dir();
			do_sandbox_none();
	check_leaks();
	return 0;
}