net/sctp: vmalloc allocation failure in sctp_setsockopt/xt_alloc_table_info

From: Andrey Konovalov
Date: Mon Nov 28 2016 - 08:00:34 EST

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Hi!

I've got the following error report while running the syzkaller fuzzer.

On commit d8e435f3ab6fea2ea324dce72b51dd7761747523 (Nov 26).

A reproducer is attached.

a.out: vmalloc: allocation failure, allocated 823562240 of 1427091456
bytes, mode:0x24000c2(GFP_KERNEL|__GFP_HIGHMEM)

oom_reaper: reaped process 3810 (a.out), now anon-rss:0kB,
file-rss:0kB, shmem-rss:0kB
a.out invoked oom-killer:
gfp_mask=0x24002c2(GFP_KERNEL|__GFP_HIGHMEM|__GFP_NOWARN), nodemask=0,
order=0, oom_score_adj=0
a.out cpuset=/ mems_allowed=0
CPU: 0 PID: 3814 Comm: a.out Not tainted 4.9.0-rc6+ #457
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
ffff880068667380 ffffffff81c73b14 ffff880068667710 ffff88006b469018
ffff880068667718 0000000000000000 ffff880068667400 ffffffff81641a87
0000000000000000 0000000000000000 0000000000000297 ffffffff84d37280
Call Trace:
[< inline >] __dump_stack lib/dump_stack.c:15
[<ffffffff81c73b14>] dump_stack+0xb3/0x10f lib/dump_stack.c:51
[<ffffffff81641a87>] dump_header.isra.21+0x16f/0x5f5 mm/oom_kill.c:416
[<ffffffff8154bad8>] oom_kill_process+0x4d8/0xab0 mm/oom_kill.c:835
[<ffffffff8154c77c>] out_of_memory+0x2dc/0x1790 mm/oom_kill.c:1044
[< inline >] __alloc_pages_may_oom mm/page_alloc.c:3086
[<ffffffff8155afb6>] __alloc_pages_slowpath+0x1886/0x1bf0 mm/page_alloc.c:3683
[<ffffffff8155b8e2>] __alloc_pages_nodemask+0x5c2/0x710 mm/page_alloc.c:3781
[<ffffffff816236a4>] alloc_pages_current+0xf4/0x400 mm/mempolicy.c:2072
[< inline >] alloc_pages ./include/linux/gfp.h:469
[< inline >] __vmalloc_area_node mm/vmalloc.c:1631
[<ffffffff815f8eab>] __vmalloc_node_range+0x33b/0x690 mm/vmalloc.c:1691
[< inline >] __vmalloc_node mm/vmalloc.c:1734
[< inline >] __vmalloc_node_flags mm/vmalloc.c:1748
[<ffffffff815f92cb>] vmalloc+0x5b/0x70 mm/vmalloc.c:1763
[<ffffffff82fd0893>] xt_alloc_table_info+0x83/0x120
net/netfilter/x_tables.c:961
[< inline >] do_replace net/ipv4/netfilter/ip_tables.c:1140
[<ffffffff8335b420>] do_ipt_set_ctl+0x210/0x420
net/ipv4/netfilter/ip_tables.c:1687
[< inline >] nf_sockopt net/netfilter/nf_sockopt.c:105
[<ffffffff82efdab7>] nf_setsockopt+0x67/0xc0 net/netfilter/nf_sockopt.c:114
[<ffffffff831be741>] ip_setsockopt+0xa1/0xb0 net/ipv4/ip_sockglue.c:1231
[<ffffffff832700d5>] udp_setsockopt+0x45/0x80 net/ipv4/udp.c:2085
[<ffffffff8346b31f>] ipv6_setsockopt+0x11f/0x140 net/ipv6/ipv6_sockglue.c:892
[<ffffffff83a6cd5d>] sctp_setsockopt+0x15d/0x3d70 net/sctp/socket.c:3788
[<ffffffff82ca40e6>] sock_common_setsockopt+0x96/0xd0 net/core/sock.c:2690
[< inline >] SYSC_setsockopt net/socket.c:1757
[<ffffffff82ca10c4>] SyS_setsockopt+0x154/0x240 net/socket.c:1736
[<ffffffff840f2c41>] entry_SYSCALL_64_fastpath+0x1f/0xc2
arch/x86/entry/entry_64.S:209
CPU: 1 PID: 3810 Comm: a.out Not tainted 4.9.0-rc6+ #457
Mem-Info:
active_anon:1938 inactive_anon:75 isolated_anon:0
active_file:14 inactive_file:30 isolated_file:4
unevictable:0 dirty:0 writeback:0 unstable:0
slab_reclaimable:3316 slab_unreclaimable:9767
mapped:21 shmem:81 pagetables:309 bounce:0
free:1 free_pcp:75 free_cma:0
Node 0 active_anon:7752kB inactive_anon:300kB active_file:56kB
inactive_file:120kB unevictable:0kB isolated(anon):0kB
isolated(file):16kB mapped:84kB dirty:0kB writeback:0kB shmem:324kB
writeback_tmp:0kB unstable:0kB pages_scanned:134 all_unreclaimable? no
Node 0 DMA free:4kB min:48kB low:60kB high:72kB active_anon:0kB
inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB
writepending:0kB present:15992kB managed:15908kB mlocked:0kB
slab_reclaimable:0kB slab_unreclaimable:8kB kernel_stack:0kB
pagetables:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
lowmem_reserve[]: 0 1641 1641 1641
Node 0 DMA32 free:0kB min:5156kB low:6836kB high:8516kB
active_anon:7752kB inactive_anon:300kB active_file:56kB
inactive_file:120kB unevictable:0kB writepending:0kB present:2080760kB
managed:1684640kB mlocked:0kB slab_reclaimable:13264kB
slab_unreclaimable:39060kB kernel_stack:2944kB pagetables:1236kB
bounce:0kB free_pcp:300kB local_pcp:120kB free_cma:0kB
lowmem_reserve[]: 0 0 0 0
Node 0 DMA: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB
0*1024kB 0*2048kB 0*4096kB = 0kB
Node 0 DMA32: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB
0*1024kB 0*2048kB 0*4096kB = 0kB
Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
148 total pagecache pages
0 pages in swap cache
Swap cache stats: add 0, delete 0, find 0/0
Free swap = 0kB
Total swap = 0kB
524188 pages RAM
0 pages HighMem/MovableOnly
99051 pages reserved
[ pid ] uid tgid total_vm rss nr_ptes nr_pmds swapents
oom_score_adj name
0 1767 5346 133 16 3 0 -1000 udevd
0 1876 5315 122 15 3 0 -1000 udevd
0 1877 5315 122 15 3 0 -1000 udevd
0 3541 2493 573 8 3 0 0 dhclient
0 3676 13231 171 22 3 0 0 rsyslogd
0 3725 4725 52 15 3 0 0 cron
0 3751 12490 155 28 3 0 -1000 sshd
0 3775 3694 43 13 3 0 0 getty
0 3776 3694 43 13 3 0 0 getty
0 3777 3694 42 13 3 0 0 getty
0 3778 3694 41 13 3 0 0 getty
0 3779 3694 44 13 3 0 0 getty
0 3780 3694 43 13 3 0 0 getty
0 3785 3649 44 12 3 0 0 getty
0 3797 17818 205 39 3 0 0 sshd
0 3800 4474 126 15 3 0 0 bash
0 3804 2053 22 9 3 0 0 a.out
0 3805 2053 26 9 3 0 0 a.out
0 3806 18488 0 18 3 0 0 a.out
// autogenerated by syzkaller (http://github.com/google/syzkaller)

#ifndef __NR_mmap
#define __NR_mmap 9
#endif
#ifndef __NR_setsockopt
#define __NR_setsockopt 54
#endif
#ifndef __NR_syz_fuse_mount
#define __NR_syz_fuse_mount 1000004
#endif
#ifndef __NR_socket
#define __NR_socket 41
#endif
#ifndef __NR_syz_emit_ethernet
#define __NR_syz_emit_ethernet 1000006
#endif
#ifndef __NR_syz_fuseblk_mount
#define __NR_syz_fuseblk_mount 1000005
#endif
#ifndef __NR_syz_open_dev
#define __NR_syz_open_dev 1000002
#endif
#ifndef __NR_syz_open_pts
#define __NR_syz_open_pts 1000003
#endif
#ifndef __NR_syz_test
#define __NR_syz_test 1000001
#endif

#define SYZ_SANDBOX_NONE 1
#define SYZ_REPEAT 1

#define _GNU_SOURCE

#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/wait.h>

#include <linux/capability.h>
#include <linux/if.h>
#include <linux/if_tun.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 <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 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);
exit(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);
exit(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)
{
if (__atomic_load_n(&skip_segv, __ATOMIC_RELAXED))
_longjmp(segv_env, 1);
exit(sig);
}

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); \
}

static uintptr_t syz_open_dev(uintptr_t a0, uintptr_t a1, uintptr_t a2)
{
if (a0 == 0xc || a0 == 0xb) {
char buf[128];
sprintf(buf, "/dev/%s/%d:%d", a0 == 0xc ? "char" : "block",
(uint8_t)a1, (uint8_t)a2);
return open(buf, O_RDWR, 0);
} else {
char buf[1024];
char* hash;
strncpy(buf, (char*)a0, sizeof(buf));
buf[sizeof(buf) - 1] = 0;
while ((hash = strchr(buf, '#'))) {
*hash = '0' + (char)(a1 % 10);
a1 /= 10;
}
return open(buf, a2, 0);
}
}

static uintptr_t syz_open_pts(uintptr_t a0, uintptr_t a1)
{
int ptyno = 0;
if (ioctl(a0, TIOCGPTN, &ptyno))
return -1;
char buf[128];
sprintf(buf, "/dev/pts/%d", ptyno);
return open(buf, a1, 0);
}

static uintptr_t syz_fuse_mount(uintptr_t a0, uintptr_t a1,
uintptr_t a2, uintptr_t a3,
uintptr_t a4, uintptr_t a5)
{
uint64_t target = a0;
uint64_t mode = a1;
uint64_t uid = a2;
uint64_t gid = a3;
uint64_t maxread = a4;
uint64_t flags = a5;

int fd = open("/dev/fuse", O_RDWR);
if (fd == -1)
return fd;
char buf[1024];
sprintf(buf, "fd=%d,user_id=%ld,group_id=%ld,rootmode=0%o", fd,
(long)uid, (long)gid, (unsigned)mode & ~3u);
if (maxread != 0)
sprintf(buf + strlen(buf), ",max_read=%ld", (long)maxread);
if (mode & 1)
strcat(buf, ",default_permissions");
if (mode & 2)
strcat(buf, ",allow_other");
syscall(SYS_mount, "", target, "fuse", flags, buf);
return fd;
}

static uintptr_t syz_fuseblk_mount(uintptr_t a0, uintptr_t a1,
uintptr_t a2, uintptr_t a3,
uintptr_t a4, uintptr_t a5,
uintptr_t a6, uintptr_t a7)
{
uint64_t target = a0;
uint64_t blkdev = a1;
uint64_t mode = a2;
uint64_t uid = a3;
uint64_t gid = a4;
uint64_t maxread = a5;
uint64_t blksize = a6;
uint64_t flags = a7;

int fd = open("/dev/fuse", O_RDWR);
if (fd == -1)
return fd;
if (syscall(SYS_mknodat, AT_FDCWD, blkdev, S_IFBLK, makedev(7, 199)))
return fd;
char buf[256];
sprintf(buf, "fd=%d,user_id=%ld,group_id=%ld,rootmode=0%o", fd,
(long)uid, (long)gid, (unsigned)mode & ~3u);
if (maxread != 0)
sprintf(buf + strlen(buf), ",max_read=%ld", (long)maxread);
if (blksize != 0)
sprintf(buf + strlen(buf), ",blksize=%ld", (long)blksize);
if (mode & 1)
strcat(buf, ",default_permissions");
if (mode & 2)
strcat(buf, ",allow_other");
syscall(SYS_mount, blkdev, target, "fuseblk", flags, buf);
return fd;
}

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);
case __NR_syz_test:
return 0;
case __NR_syz_open_dev:
return syz_open_dev(a0, a1, a2);
case __NR_syz_open_pts:
return syz_open_pts(a0, a1);
case __NR_syz_fuse_mount:
return syz_fuse_mount(a0, a1, a2, a3, a4, a5);
case __NR_syz_fuseblk_mount:
return syz_fuseblk_mount(a0, a1, a2, a3, a4, a5, a6, a7);
}
}

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 do_sandbox_none()
{
int pid = fork();
if (pid)
return pid;
sandbox_common();
loop();
exit(1);
}

static void remove_dir(const char* dir)
{
DIR* dp;
struct dirent* ep;
int iter = 0;
int i;
retry:
dp = opendir(dir);
if (dp == NULL) {
if (errno == EMFILE) {
exitf("opendir(%s) failed due to NOFILE, exiting");
}
exitf("opendir(%s) failed", dir);
}
while ((ep = readdir(dp))) {
if (strcmp(ep->d_name, ".") == 0 || strcmp(ep->d_name, "..") == 0)
continue;
char filename[FILENAME_MAX];
snprintf(filename, sizeof(filename), "%s/%s", dir, ep->d_name);
struct stat st;
if (lstat(filename, &st))
exitf("lstat(%s) failed", filename);
if (S_ISDIR(st.st_mode)) {
remove_dir(filename);
continue;
}
for (i = 0;; i++) {
debug("unlink(%s)\n", filename);
if (unlink(filename) == 0)
break;
if (errno == EROFS) {
debug("ignoring EROFS\n");
break;
}
if (errno != EBUSY || i > 100)
exitf("unlink(%s) failed", filename);
debug("umount(%s)\n", filename);
if (umount2(filename, MNT_DETACH))
exitf("umount(%s) failed", filename);
}
}
closedir(dp);
for (i = 0;; i++) {
debug("rmdir(%s)\n", dir);
if (rmdir(dir) == 0)
break;
if (i < 100) {
if (errno == EROFS) {
debug("ignoring EROFS\n");
break;
}
if (errno == EBUSY) {
debug("umount(%s)\n", dir);
if (umount2(dir, MNT_DETACH))
exitf("umount(%s) failed", dir);
continue;
}
if (errno == ENOTEMPTY) {
if (iter < 100) {
iter++;
goto retry;
}
}
}
exitf("rmdir(%s) failed", dir);
}
}

static uint64_t current_time_ms()
{
struct timespec ts;

if (clock_gettime(CLOCK_MONOTONIC, &ts))
fail("clock_gettime failed");
return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
}

static void test();

void loop()
{
int iter;
for (iter = 0;; iter++) {
char cwdbuf[256];
sprintf(cwdbuf, "./%d", iter);
if (mkdir(cwdbuf, 0777))
fail("failed to mkdir");
int pid = fork();
if (pid < 0)
fail("clone failed");
if (pid == 0) {
prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
setpgrp();
if (chdir(cwdbuf))
fail("failed to chdir");
test();
exit(0);
}
int status = 0;
uint64_t start = current_time_ms();
for (;;) {
int res = waitpid(pid, &status, __WALL | WNOHANG);
int errno0 = errno;
if (res == pid)
break;
usleep(1000);
if (current_time_ms() - start > 5 * 1000) {
kill(-pid, SIGKILL);
kill(pid, SIGKILL);
waitpid(pid, &status, __WALL);
break;
}
}
remove_dir(cwdbuf);
}
}

long r[5];
void* thr(void* arg)
{
switch ((long)arg) {
case 0:
r[0] =
execute_syscall(__NR_mmap, 0x20000000ul, 0xa000ul, 0x3ul,
0x32ul, 0xfffffffffffffffful, 0x0ul, 0, 0, 0);
break;
case 1:
r[1] = execute_syscall(__NR_socket, 0xaul, 0x5ul, 0x84ul, 0, 0, 0,
0, 0, 0);
break;
case 2:
r[2] = execute_syscall(__NR_socket, 0x1ful, 0x3ul, 0x6ul, 0, 0, 0,
0, 0, 0);
break;
case 3:
NONFAILING(memcpy(
(void*)0x20009000,
"\x83\x15\xf6\xdb\x47\x14\xae\xe2\x8d\xb8\x4d\xb9\x0f\x32\xe7"
"\xf5\xbc\xa6\xae\x9a\x2f\x19\xed\xf0\x75\x6a\x0b\xf0\x00\xe9"
"\xe1\x0e\xb4\xa5\x19\x08\x88\xfc\x8b\x2d\xe2\x9a\x0f\x55\x00"
"\x00\x00\x00\x00\x08\x27\xab\x8e\x7d\xcb\xcc\x15\x4e\x79\xe2"
"\xd9\xca\x15\xc3\x66\xbd\x44\xa8\x53\x1f\xda\xab\xce\x98\x39"
"\x40\x4e\x75\x57\xfd\x57\xc0\x01\x0b\xb0",
85));
r[4] = execute_syscall(__NR_setsockopt, r[1], 0x0ul, 0x40ul,
0x20009000ul, 0x55ul, 0, 0, 0, 0);
break;
}
return 0;
}

void test()
{
long i;
pthread_t th[8];

memset(r, -1, sizeof(r));
srand(getpid());
for (i = 0; i < 4; i++) {
pthread_create(&th[i], 0, thr, (void*)i);
usleep(10000);
}
for (i = 0; i < 4; i++) {
pthread_create(&th[4 + i], 0, thr, (void*)i);
if (rand() % 2)
usleep(rand() % 10000);
}
usleep(100000);
}

int main()
{
setup_main_process();
int pid = do_sandbox_none();
int status = 0;
while (waitpid(pid, &status, __WALL) != pid) {
}
return 0;
}

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