zzoru <zzoru...@gmail.com> writes:
> net/core: BUG in copy_net_ns() (net_namespace.c)
I don't understand this failure report at all.
I don't see the connection to copy_net_ns(). And I don't see how the
suggested patch short of covering up a memory stomp could possibly make
a difference.
What am I missing?
> Hello,
>
> I've got the following error report while fuzzing the kernel with syzkaller.
>
> On commit 1bdbe227492075d058e37cb3d400e6468d0095b5
>
> Syzkaller hit 'WARNING in __alloc_pages_slowpath' bug.
>
> syz-executor561 (17453) used greatest stack depth: 25056 bytes left
> WARNING: CPU: 0 PID: 692 at mm/page_alloc.c:4415
> __alloc_pages_slowpath+0x1cb1/0x2220 mm/page_alloc.c:4386
> Kernel panic - not syncing: panic_on_warn set ...
> CPU: 0 PID: 692 Comm: kswapd0 Not tainted 5.0.0-rc1+ #4
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> Ubuntu-1.8.2-1ubuntu1 04/01/2014
> Call Trace:
> __dump_stack lib/dump_stack.c:77 [inline]
> dump_stack+0xca/0x13e lib/dump_stack.c:113
> panic+0x278/0x5bf kernel/panic.c:214
> __warn.cold.10+0x20/0x45 kernel/panic.c:571
> report_bug+0x246/0x2d0 lib/bug.c:186
> fixup_bug arch/x86/kernel/traps.c:178 [inline]
> do_error_trap+0x123/0x1e0 arch/x86/kernel/traps.c:271
> do_invalid_op+0x31/0x40 arch/x86/kernel/traps.c:290
> invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:973
> RIP: 0010:__alloc_pages_slowpath+0x1cb1/0x2220 mm/page_alloc.c:4415
> Code: 8b 84 24 a8 00 00 00 e9 ea f1 ff ff 85 d2 0f 85 0b 01 00 00 48 c7
> c7 c0 5e 55 84 e8 79 f8 23 02 e9 86 f9 ff ff 44 8b 74 24 0c <0f> 0b 48
> b8 00 00 00 00 00 fc ff df 48 8b 54 24 18 48 c1 ea 03 80
> RSP: 0018:ffff8880683fedb8 EFLAGS: 00010046
> RAX: 0000000000000000 RBX: 0000000000000000 RCX: 1ffff1100d07fda4
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88807ffdd528
> RBP: dffffc0000000000 R08: 0000000000000000 R09: 000000000000067a
> R10: 0000000000000000 R11: ffff88807ffdc487 R12: 0000000000000000
> R13: ffff8880683ff010 R14: 0000000000415a00 R15: ffff8880683ff010
> __alloc_pages_nodemask+0x521/0x5f0 mm/page_alloc.c:4555
> __alloc_pages include/linux/gfp.h:473 [inline]
> __alloc_pages_node include/linux/gfp.h:486 [inline]
> kmem_getpages mm/slab.c:1398 [inline]
> cache_grow_begin+0x95/0x300 mm/slab.c:2666
> fallback_alloc+0x1ce/0x270 mm/slab.c:3208
> __do_cache_alloc mm/slab.c:3345 [inline]
> slab_alloc mm/slab.c:3373 [inline]
> kmem_cache_alloc+0x286/0x2f0 mm/slab.c:3541
> create_object+0x83/0x880 mm/kmemleak.c:578
> kmemleak_alloc_recursive include/linux/kmemleak.h:55 [inline]
> slab_post_alloc_hook mm/slab.h:442 [inline]
> slab_alloc mm/slab.c:3381 [inline]
> kmem_cache_alloc+0x18f/0x2f0 mm/slab.c:3541
> mempool_alloc+0x13e/0x340 mm/mempool.c:385
> bio_alloc_bioset+0x36f/0x5d0 block/bio.c:489
> bio_alloc include/linux/bio.h:393 [inline]
> submit_bh_wbc.isra.57+0x128/0x680 fs/buffer.c:3061
> __block_write_full_page+0x6e8/0xcd0 fs/buffer.c:1765
> block_write_full_page+0x202/0x250 fs/buffer.c:2955
> pageout mm/vmscan.c:865 [inline]
> shrink_page_list+0x220f/0x3800 mm/vmscan.c:1383
> shrink_inactive_list+0x3c2/0xaa0 mm/vmscan.c:1961
> shrink_list mm/vmscan.c:2273 [inline]
> shrink_node_memcg.constprop.83+0x4bf/0x10e0 mm/vmscan.c:2538
> shrink_node+0x162/0xd10 mm/vmscan.c:2753
> kswapd_shrink_node mm/vmscan.c:3516 [inline]
> balance_pgdat+0x47f/0xc00 mm/vmscan.c:3674
> kswapd+0x57c/0xde0 mm/vmscan.c:3929
> kthread+0x347/0x410 kernel/kthread.c:246
> ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
> Dumping ftrace buffer:
> (ftrace buffer empty)
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
>
>
> Syzkaller reproducer:
> # {Threaded:false Collide:false Repeat:true RepeatTimes:0 Procs:8
> Sandbox:none Fault:false FaultCall:-1 FaultNth:0 EnableTun:false
> UseTmpDir:true EnableCgroups:false EnableNetdev:true ResetNet:false
> HandleSegv:false Repro:false Trace:false}
> unshare(0x40000000)
>
>
> C reproducer:
> // autogenerated by syzkaller (https://github.com/google/syzkaller)
>
> #define _GNU_SOURCE
>
> #include <arpa/inet.h>
> #include <dirent.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 <signal.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/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 void sleep_ms(uint64_t ms)
> {
> usleep(ms * 1000);
> }
>
> 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::%02hx"
> #define DEV_MAC 0x00aaaaaaaaaa
> 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);
> 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::%02hx:%02hx", 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 int do_sandbox_none(void)
> {
> if (unshare(CLONE_NEWPID)) {
> }
> int pid = fork();
> if (pid != 0)
> return wait_for_loop(pid);
> setup_common();
> sandbox_common();
> initialize_netdevices_init();
> if (unshare(CLONE_NEWNET)) {
> }
> initialize_netdevices();
> loop();
> exit(1);
> }
>
> #define FS_IOC_SETFLAGS _IOW('f', 2, long)
> static void remove_dir(const char* dir)
> {
> DIR* dp;
> struct dirent* ep;
> int iter = 0;
> retry:
> while (umount2(dir, MNT_DETACH) == 0) {
> }
> dp = opendir(dir);
> if (dp == NULL) {
> if (errno == EMFILE) {
> exit(1);
> }
> exit(1);
> }
> 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);
> while (umount2(filename, MNT_DETACH) == 0) {
> }
> struct stat st;
> if (lstat(filename, &st))
> exit(1);
> if (S_ISDIR(st.st_mode)) {
> remove_dir(filename);
> continue;
> }
> int i;
> for (i = 0;; i++) {
> if (unlink(filename) == 0)
> break;
> if (errno == EPERM) {
> int fd = open(filename, O_RDONLY);
> if (fd != -1) {
> long flags = 0;
> if (ioctl(fd, FS_IOC_SETFLAGS, &flags) == 0)
> close(fd);
> continue;
> }
> }
> if (errno == EROFS) {
> break;
> }
> if (errno != EBUSY || i > 100)
> exit(1);
> if (umount2(filename, MNT_DETACH))
> exit(1);
> }
> }
> closedir(dp);
> int i;
> for (i = 0;; i++) {
> if (rmdir(dir) == 0)
> break;
> if (i < 100) {
> if (errno == EPERM) {
> int fd = open(dir, O_RDONLY);
> if (fd != -1) {
> long flags = 0;
> if (ioctl(fd, FS_IOC_SETFLAGS, &flags) == 0)
> close(fd);
> continue;
> }
> }
> if (errno == EROFS) {
> break;
> }
> if (errno == EBUSY) {
> if (umount2(dir, MNT_DETACH))
> exit(1);
> continue;
> }
> if (errno == ENOTEMPTY) {
> if (iter < 100) {
> iter++;
> goto retry;
> }
> }
> }
> exit(1);
> }
> }
>
> static void kill_and_wait(int pid, int* status)
> {
> kill(-pid, SIGKILL);
> kill(pid, SIGKILL);
> int i;
> for (i = 0; i < 100; i++) {
> if (waitpid(-1, status, WNOHANG | __WALL) == pid)
> return;
> usleep(1000);
> }
> DIR* dir = opendir("/sys/fs/fuse/connections");
> if (dir) {
> for (;;) {
> struct dirent* ent = readdir(dir);
> if (!ent)
> break;
> if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0)
> continue;
> char abort[300];
> snprintf(abort, sizeof(abort), "/sys/fs/fuse/connections/%s/abort",
> ent->d_name);
> int fd = open(abort, O_WRONLY);
> if (fd == -1) {
> continue;
> }
> if (write(fd, abort, 1) < 0) {
> }
> close(fd);
> }
> closedir(dir);
> } else {
> }
> while (waitpid(-1, status, __WALL) != pid) {
> }
> }
>
> #define SYZ_HAVE_SETUP_TEST 1
> static void setup_test()
> {
> prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
> setpgrp();
> }
>
> #define SYZ_HAVE_RESET_TEST 1
> static void reset_test()
> {
> int fd;
> for (fd = 3; fd < 30; fd++)
> close(fd);
> }
>
> static void execute_one(void);
>
> #define WAIT_FLAGS __WALL
>
> static void loop(void)
> {
> int iter;
> for (iter = 0;; iter++) {
> char cwdbuf[32];
> sprintf(cwdbuf, "./%d", iter);
> if (mkdir(cwdbuf, 0777))
> exit(1);
> int pid = fork();
> if (pid < 0)
> exit(1);
> if (pid == 0) {
> if (chdir(cwdbuf))
> exit(1);
> setup_test();
> execute_one();
> reset_test();
> exit(0);
> }
> int status = 0;
> uint64_t start = current_time_ms();
> for (;;) {
> if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid)
> break;
> sleep_ms(1);
> if (current_time_ms() - start < 5 * 1000)
> continue;
> kill_and_wait(pid, &status);
> break;
> }
> remove_dir(cwdbuf);
> }
> }
>
> void execute_one(void)
> {
> syscall(__NR_unshare, 0x40000000);
> }
> int main(void)
> {
> syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0);
> for (procid = 0; procid < 8; procid++) {
> if (fork() == 0) {
> use_temporary_dir();
> do_sandbox_none();
> }
> }
> sleep(1000000);
> return 0;
> }
>
>
> I reviewed kernel code and found a bug that
> net_drop_ns func doesn't call net_free func when refcount_dec_and_test's
> return value is zero.
Yes. We don't call net_free when the reference count does not decrement
to zero. The reference count is initialized to 1 a few lines above the
section of code in your patch so that should not be a problem.
> or
> when rv = down_read_killable(&pernet_ops_rwsem) < 0, it doesn't need to
> call refcount_dec_and_test.
It doesn't need to but it should be harmless.
> https://github.com/torvalds/linux/commit/5ba049a5cc8e24a1643df75bbf65b4efa070fa74#diff-9312644e2968a45510bacdd2b2872ad2
> (I can't reproduce this bug on v4.15 , and
> 1bdbe227492075d058e37cb3d400e6468d0095b5 with my patch. Because of the
> previous version of kernel doesn't have this bug.)
> This bug can lead to memory leak or DOS.
>
> I made a patch for this bug. (just revert to a before commit)
What am I missing?
The only thing I can see your patch doing is covering up a memory stomp
that has the effect of changing the value of net->passive. I am not
really keen on hiding bugs of that kind.
> diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
> index b02fb19df2cc..9de0ade14956 100644
> --- a/net/core/net_namespace.c
> +++ b/net/core/net_namespace.c
> @@ -431,15 +431,18 @@ struct net *copy_net_ns(unsigned long flags,
> get_user_ns(user_ns);
>
> rv = down_read_killable(&pernet_ops_rwsem);
> - if (rv < 0)
> - goto put_userns;
> + if (rv < 0){
> + net_free(net);
> + dec_net_namespaces(ucounts);
> + put_user_ns(user_ns);
> + return ERR_PTR(rv);
> + }
>
> rv = setup_net(net, user_ns);
>
> up_read(&pernet_ops_rwsem);
>
> if (rv < 0) {
> -put_userns:
> put_user_ns(user_ns);
> net_drop_ns(net);
> dec_ucounts:
>
> and, sorry for my encrypted mails.
Eric
