Re: net: heap out-of-bounds in fib6_clean_node/rt6_fill_node/fib6_age/fib6_prune_clone

From: Andrey Konovalov
Date: Tue Apr 18 2017 - 16:44:09 EST

Next message: Mikulas Patocka: "Re: [PATCH] X86: don't report PAT on CPUs that don't support it"
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Next in thread: David Ahern: "Re: net: heap out-of-bounds in fib6_clean_node/rt6_fill_node/fib6_age/fib6_prune_clone"
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Hi!

I've finally managed to reproduce one of the crashes on commit
4f7d029b9bf009fbee76bb10c0c4351a1870d2f3 (4.11-rc7).

I'm not sure if this bug has the same root cause as the first one
reported in this thread, but it definitely has to do with ipv6
routing.

C reproducer, syzkaller program and my .config are attached.

Thanks!

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
Modules linked in:
CPU: 1 PID: 4035 Comm: a.out Not tainted 4.11.0-rc7+ #250
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
task: ffff880069809600 task.stack: ffff880062dc8000
RIP: 0010:ip6_rt_cache_alloc+0xa6/0x560 net/ipv6/route.c:975
RSP: 0018:ffff880062dced30 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: ffff8800670561c0 RCX: 0000000000000006
RDX: 0000000000000003 RSI: ffff880062dcfb28 RDI: 0000000000000018
RBP: ffff880062dced68 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffff880062dcfb28 R14: dffffc0000000000 R15: 0000000000000000
FS: 00007feebe37e7c0(0000) GS:ffff88006cb00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000205a0fe4 CR3: 000000006b5c9000 CR4: 00000000000006e0
Call Trace:
ip6_pol_route+0x1512/0x1f20 net/ipv6/route.c:1128
ip6_pol_route_output+0x4c/0x60 net/ipv6/route.c:1212
fib6_rule_action+0x261/0x8a0 net/ipv6/fib6_rules.c:100
fib_rules_lookup+0x3be/0xbc0 net/core/fib_rules.c:265
fib6_rule_lookup+0x175/0x360 net/ipv6/fib6_rules.c:44
ip6_route_output_flags+0x260/0x2f0 net/ipv6/route.c:1240
ip6_route_output ./include/net/ip6_route.h:79
ip6_dst_lookup_tail+0xd5e/0x18b0 net/ipv6/ip6_output.c:959
ip6_dst_lookup_flow+0xb1/0x260 net/ipv6/ip6_output.c:1082
rawv6_sendmsg+0x11b2/0x42e0 net/ipv6/raw.c:903
inet_sendmsg+0x164/0x5b0 net/ipv4/af_inet.c:762
sock_sendmsg_nosec net/socket.c:633
sock_sendmsg+0xca/0x110 net/socket.c:643
SYSC_sendto+0x660/0x810 net/socket.c:1696
SyS_sendto+0x40/0x50 net/socket.c:1664
entry_SYSCALL_64_fastpath+0x1f/0xc2 arch/x86/entry/entry_64.S:204
RIP: 0033:0x7feebda90b79
RSP: 002b:000000000072fee8 EFLAGS: 00000206 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007ffe1f920180 RCX: 00007feebda90b79
RDX: 0000000000000000 RSI: 0000000020fd0fd0 RDI: 0000000000000004
RBP: 0000000000400f30 R08: 00000000205a0fe4 R09: 000000000000001c
R10: 0000000000000800 R11: 0000000000000206 R12: 0000000000000000
R13: 00007ffe1f920180 R14: 0000000000000000 R15: 0000000000000000
Code: 03 80 3c 02 00 0f 85 37 04 00 00 4d 8b 64 24 40 e8 90 dd 82 fd
49 8d 7c 24 18 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80>
3c 02 00 0f 85 61 04 00 00 49 8b 74 24 18 48 b8 00 00 00 00
RIP: ip6_rt_cache_alloc+0xa6/0x560 RSP: ffff880062dced30
---[ end trace 9f58077ffa8cf9c0 ]---

Attachment: ip6_rt_cache_alloc-crash-log
Description: Binary data

// autogenerated by syzkaller (http://github.com/google/syzkaller)

#ifndef __NR_mmap
#define __NR_mmap 9
#endif
#ifndef __NR_socket
#define __NR_socket 41
#endif
#ifndef __NR_ioctl
#define __NR_ioctl 16
#endif
#ifndef __NR_sendto
#define __NR_sendto 44
#endif

#define _GNU_SOURCE

#include <sys/ioctl.h>
#include <sys/mman.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/wait.h>

#include <linux/capability.h>
#include <linux/if.h>
#include <linux/if_tun.h>
#include <linux/kvm.h>
#include <linux/sched.h>
#include <net/if_arp.h>

#include <assert.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#include <pthread.h>
#include <setjmp.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

const int kFailStatus = 67;
const int kErrorStatus = 68;
const int kRetryStatus = 69;

__attribute__((noreturn)) void doexit(int status)
{
volatile unsigned i;
syscall(__NR_exit_group, status);
for (i = 0;; i++) {
}
}

__attribute__((noreturn)) void fail(const char* msg, ...)
{
int e = errno;
fflush(stdout);
va_list args;
va_start(args, msg);
vfprintf(stderr, msg, args);
va_end(args);
fprintf(stderr, " (errno %d)\n", e);
doexit((e == ENOMEM || e == EAGAIN) ? kRetryStatus : kFailStatus);
}

__attribute__((noreturn)) void exitf(const char* msg, ...)
{
int e = errno;
fflush(stdout);
va_list args;
va_start(args, msg);
vfprintf(stderr, msg, args);
va_end(args);
fprintf(stderr, " (errno %d)\n", e);
doexit(kRetryStatus);
}

static int flag_debug;

void debug(const char* msg, ...)
{
if (!flag_debug)
return;
va_list args;
va_start(args, msg);
vfprintf(stdout, msg, args);
va_end(args);
fflush(stdout);
}

__thread int skip_segv;
__thread jmp_buf segv_env;

static void segv_handler(int sig, siginfo_t* info, void* uctx)
{
uintptr_t addr = (uintptr_t)info->si_addr;
const uintptr_t prog_start = 1 << 20;
const uintptr_t prog_end = 100 << 20;
if (__atomic_load_n(&skip_segv, __ATOMIC_RELAXED) &&
(addr < prog_start || addr > prog_end)) {
debug("SIGSEGV on %p, skipping\n", addr);
_longjmp(segv_env, 1);
}
debug("SIGSEGV on %p, exiting\n", addr);
doexit(sig);
for (;;) {
}
}

static void install_segv_handler()
{
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_sigaction = segv_handler;
sa.sa_flags = SA_NODEFER | SA_SIGINFO;
sigaction(SIGSEGV, &sa, NULL);
sigaction(SIGBUS, &sa, NULL);
}

#define NONFAILING(...) \
{ \
__atomic_fetch_add(&skip_segv, 1, __ATOMIC_SEQ_CST); \
if (_setjmp(segv_env) == 0) { \
__VA_ARGS__; \
} \
__atomic_fetch_sub(&skip_segv, 1, __ATOMIC_SEQ_CST); \
}

#define BITMASK_LEN(type, bf_len) (type)((1ull << (bf_len)) - 1)

#define BITMASK_LEN_OFF(type, bf_off, bf_len) \
(type)(BITMASK_LEN(type, (bf_len)) << (bf_off))

#define STORE_BY_BITMASK(type, addr, val, bf_off, bf_len) \
if ((bf_off) == 0 && (bf_len) == 0) { \
*(type*)(addr) = (type)(val); \
} else { \
type new_val = *(type*)(addr); \
new_val &= ~BITMASK_LEN_OFF(type, (bf_off), (bf_len)); \
new_val |= ((type)(val)&BITMASK_LEN(type, (bf_len))) << (bf_off); \
*(type*)(addr) = new_val; \
}

static uintptr_t execute_syscall(int nr, uintptr_t a0, uintptr_t a1,
uintptr_t a2, uintptr_t a3,
uintptr_t a4, uintptr_t a5,
uintptr_t a6, uintptr_t a7,
uintptr_t a8)
{
switch (nr) {
default:
return syscall(nr, a0, a1, a2, a3, a4, a5);
}
}

static void setup_main_process()
{
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_handler = SIG_IGN;
syscall(SYS_rt_sigaction, 0x20, &sa, NULL, 8);
syscall(SYS_rt_sigaction, 0x21, &sa, NULL, 8);
install_segv_handler();

char tmpdir_template[] = "./syzkaller.XXXXXX";
char* tmpdir = mkdtemp(tmpdir_template);
if (!tmpdir)
fail("failed to mkdtemp");
if (chmod(tmpdir, 0777))
fail("failed to chmod");
if (chdir(tmpdir))
fail("failed to chdir");
}

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 = 128 << 20;
setrlimit(RLIMIT_AS, &rlim);
rlim.rlim_cur = rlim.rlim_max = 1 << 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);

unshare(CLONE_NEWNS);
unshare(CLONE_NEWIPC);
unshare(CLONE_IO);
}

static int real_uid;
static int real_gid;
static int epid;
static bool etun;
__attribute__((aligned(64 << 10))) static char sandbox_stack[1 << 20];

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) {
close(fd);
return false;
}
close(fd);
return true;
}

static int namespace_sandbox_proc(void* arg)
{
sandbox_common();

write_file("/proc/self/setgroups", "deny");
if (!write_file("/proc/self/uid_map", "0 %d 1\n", real_uid))
fail("write of /proc/self/uid_map failed");
if (!write_file("/proc/self/gid_map", "0 %d 1\n", real_gid))
fail("write of /proc/self/gid_map failed");

if (mkdir("./syz-tmp", 0777))
fail("mkdir(syz-tmp) failed");
if (mount("", "./syz-tmp", "tmpfs", 0, NULL))
fail("mount(tmpfs) failed");
if (mkdir("./syz-tmp/newroot", 0777))
fail("mkdir failed");
if (mkdir("./syz-tmp/newroot/dev", 0700))
fail("mkdir failed");
if (mount("/dev", "./syz-tmp/newroot/dev", NULL,
MS_BIND | MS_REC | MS_PRIVATE, NULL))
fail("mount(dev) failed");
if (mkdir("./syz-tmp/pivot", 0777))
fail("mkdir failed");
if (syscall(SYS_pivot_root, "./syz-tmp", "./syz-tmp/pivot")) {
debug("pivot_root failed");
if (chdir("./syz-tmp"))
fail("chdir failed");
} else {
if (chdir("/"))
fail("chdir failed");
if (umount2("./pivot", MNT_DETACH))
fail("umount failed");
}
if (chroot("./newroot"))
fail("chroot failed");
if (chdir("/"))
fail("chdir failed");

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))
fail("capget failed");
cap_data[0].effective &= ~(1 << CAP_SYS_PTRACE);
cap_data[0].permitted &= ~(1 << CAP_SYS_PTRACE);
cap_data[0].inheritable &= ~(1 << CAP_SYS_PTRACE);
if (syscall(SYS_capset, &cap_hdr, &cap_data))
fail("capset failed");

loop();
doexit(1);
}

static int do_sandbox_namespace(int executor_pid, bool enable_tun)
{
real_uid = getuid();
real_gid = getgid();
epid = executor_pid;
etun = enable_tun;
mprotect(sandbox_stack, 4096, PROT_NONE);
return clone(
namespace_sandbox_proc,
&sandbox_stack[sizeof(sandbox_stack) - 64],
CLONE_NEWUSER | CLONE_NEWPID | CLONE_NEWUTS | CLONE_NEWNET, NULL);
}

long r[67];
void loop()
{
memset(r, -1, sizeof(r));
r[0] = execute_syscall(__NR_mmap, 0x2057b000ul, 0x2000ul, 0x3ul,
0x32ul, 0xfffffffffffffffful, 0x0ul, 0, 0, 0);
r[1] = execute_syscall(__NR_socket, 0xaul, 0x1ul, 0x84ul, 0, 0, 0, 0,
0, 0);
NONFAILING(*(uint8_t*)0x2057cfb0 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfb1 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfb2 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfb3 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfb4 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfb5 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfb6 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfb7 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfb8 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfb9 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfba = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfbb = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfbc = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfbd = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfbe = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfbf = (uint8_t)0x0);
NONFAILING(*(uint64_t*)0x2057cfc0 = (uint64_t)0x0);
NONFAILING(*(uint64_t*)0x2057cfc8 = (uint64_t)0x100000000000000);
NONFAILING(*(uint8_t*)0x2057cfd0 = (uint8_t)0xfd);
NONFAILING(*(uint8_t*)0x2057cfd1 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfd2 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfd3 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfd4 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfd5 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfd6 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfd7 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfd8 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfd9 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfda = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfdb = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfdc = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfdd = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfde = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2057cfdf = (uint8_t)0xaa);
NONFAILING(*(uint32_t*)0x2057cfe0 = (uint32_t)0x4);
NONFAILING(*(uint16_t*)0x2057cfe4 = (uint16_t)0x4000000000);
NONFAILING(*(uint16_t*)0x2057cfe6 = (uint16_t)0x7);
NONFAILING(*(uint32_t*)0x2057cfe8 = (uint32_t)0x100);
NONFAILING(*(uint64_t*)0x2057cff0 = (uint64_t)0x80000001);
NONFAILING(*(uint32_t*)0x2057cff8 = (uint32_t)0x40000000);
NONFAILING(*(uint32_t*)0x2057cffc = (uint32_t)0x9);
r[43] = execute_syscall(__NR_ioctl, r[1], 0x890bul, 0x2057cfb0ul, 0,
0, 0, 0, 0, 0);
r[44] = execute_syscall(__NR_mmap, 0x20000000ul, 0xfd0000ul, 0x1ul,
0x32ul, 0xfffffffffffffffful, 0x0ul, 0, 0, 0);
r[45] = execute_syscall(__NR_socket, 0xaul, 0x803ul, 0xfful, 0, 0, 0,
0, 0, 0);
NONFAILING(*(uint16_t*)0x205a0fe4 = (uint16_t)0xa);
NONFAILING(*(uint16_t*)0x205a0fe6 = (uint16_t)0x234e);
NONFAILING(*(uint32_t*)0x205a0fe8 = (uint32_t)0x6);
NONFAILING(*(uint8_t*)0x205a0fec = (uint8_t)0xfd);
NONFAILING(*(uint8_t*)0x205a0fed = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x205a0fee = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x205a0fef = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x205a0ff0 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x205a0ff1 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x205a0ff2 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x205a0ff3 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x205a0ff4 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x205a0ff5 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x205a0ff6 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x205a0ff7 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x205a0ff8 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x205a0ff9 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x205a0ffa = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x205a0ffb = (uint8_t)0xbb);
NONFAILING(*(uint32_t*)0x205a0ffc = (uint32_t)0x1);
r[66] = execute_syscall(__NR_sendto, r[45], 0x20fd0fd0ul, 0x0ul,
0x800ul, 0x205a0fe4ul, 0x1cul, 0, 0, 0);
}
int main()
{
setup_main_process();
int pid = do_sandbox_namespace(0, false);
int status = 0;
while (waitpid(pid, &status, __WALL) != pid) {
}
return 0;
}

Attachment: .config
Description: Binary data

Next message: Mikulas Patocka: "Re: [PATCH] X86: don't report PAT on CPUs that don't support it"
Previous message: Kees Cook: "Re: [PATCH 3/4] KASLR: Handle memory limit specified by memmap and mem option"
Next in thread: David Ahern: "Re: net: heap out-of-bounds in fib6_clean_node/rt6_fill_node/fib6_age/fib6_prune_clone"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]