Hi, I've got the following error report while fuzzing the kernel with syzkaller.
On commit 926af6273fc683cd98cd0ce7bf0d04a02eed6742. A reproducer and .config are attached kernel BUG at ./include/linux/skbuff.h:2389! invalid opcode: 0000 [#1] SMP KASAN Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 0 PID: 9315 Comm: syz-executor2 Not tainted 4.10.0-rc7+ #126 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 task: ffff88006861c480 task.stack: ffff88006a988000 RIP: 0010:skb_set_owner_r include/linux/skbuff.h:2389 [inline] RIP: 0010:__sock_queue_rcv_skb+0x8c0/0xda0 net/core/sock.c:425 RSP: 0018:ffff88003ec06b58 EFLAGS: 00010206 RAX: ffff88006861c480 RBX: ffff8800371c2568 RCX: 0000000000000000 RDX: 0000000000000100 RSI: 1ffff10006ba08ab RDI: ffff880035d04560 RBP: ffff88003ec06dc0 R08: 0000000000000002 R09: 0000000000000001 R10: 0000000000000000 R11: dffffc0000000000 R12: ffff880035d04540 R13: ffff88003ec06d98 R14: ffff8800371c2590 R15: ffff880035d045a0 FS: 00007fa8005ac700(0000) GS:ffff88003ec00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000004a6f68 CR3: 0000000038e25000 CR4: 00000000000006f0 Call Trace: <IRQ> sock_queue_rcv_skb+0x3a/0x50 net/core/sock.c:451 llc_sap_state_process+0x3e3/0x4e0 net/llc/llc_sap.c:220 llc_sap_rcv net/llc/llc_sap.c:294 [inline] llc_sap_handler+0x695/0x1320 net/llc/llc_sap.c:434 llc_rcv+0x6da/0xed0 net/llc/llc_input.c:208 __netif_receive_skb_core+0x1ae5/0x3400 net/core/dev.c:4190 __netif_receive_skb+0x2a/0x170 net/core/dev.c:4228 process_backlog+0xe5/0x6c0 net/core/dev.c:4839 napi_poll net/core/dev.c:5202 [inline] net_rx_action+0xe70/0x1900 net/core/dev.c:5267 __do_softirq+0x2fb/0xb7d kernel/softirq.c:284 do_softirq_own_stack+0x1c/0x30 arch/x86/entry/entry_64.S:902 </IRQ> do_softirq.part.17+0x1e8/0x230 kernel/softirq.c:328 do_softirq kernel/softirq.c:176 [inline] __local_bh_enable_ip+0x1f2/0x200 kernel/softirq.c:181 local_bh_enable include/linux/bottom_half.h:31 [inline] rcu_read_unlock_bh include/linux/rcupdate.h:971 [inline] __dev_queue_xmit+0xd87/0x2860 net/core/dev.c:3399 dev_queue_xmit+0x17/0x20 net/core/dev.c:3405 llc_build_and_send_ui_pkt+0x240/0x330 net/llc/llc_output.c:74 llc_ui_sendmsg+0x98d/0x1430 net/llc/af_llc.c:928 sock_sendmsg_nosec net/socket.c:635 [inline] sock_sendmsg+0xca/0x110 net/socket.c:645 ___sys_sendmsg+0x9d2/0xae0 net/socket.c:1985 __sys_sendmsg+0x138/0x320 net/socket.c:2019 SYSC_sendmsg net/socket.c:2030 [inline] SyS_sendmsg+0x2d/0x50 net/socket.c:2026 entry_SYSCALL_64_fastpath+0x1f/0xc2 RIP: 0033:0x4458b9 RSP: 002b:00007fa8005abb58 EFLAGS: 00000286 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 00000000004458b9 RDX: 0000000000040880 RSI: 0000000020003000 RDI: 0000000000000006 RBP: 00000000006e1b00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000286 R12: 0000000000708000 R13: 0000000000000082 R14: 0000000020000000 R15: 0000000000000000 Code: 4b 50 fe e9 b1 f8 ff ff e8 3e 4a 50 fe e9 78 f8 ff ff e8 34 4a 50 fe e9 6d f9 ff ff e8 2a 4a 50 fe e9 93 f9 ff ff e8 20 0a 26 fe <0f> 0b e8 19 0a 26 fe be 3c 01 00 00 48 c7 c7 e0 e9 22 85 e8 b8 RIP: skb_set_owner_r include/linux/skbuff.h:2389 [inline] RSP: ffff88003ec06b58 RIP: __sock_queue_rcv_skb+0x8c0/0xda0 net/core/sock.c:425 RSP: ffff88003ec06b58 ---[ end trace 58af2d02ad7f84f0 ]--- Kernel panic - not syncing: Fatal exception in interrupt Dumping ftrace buffer: (ftrace buffer empty) Kernel Offset: disabled Rebooting in 86400 seconds..
// autogenerated by syzkaller (http://github.com/google/syzkaller) #ifndef __NR_sendmsg #define __NR_sendmsg 46 #endif #ifndef __NR_mmap #define __NR_mmap 9 #endif #ifndef __NR_socket #define __NR_socket 41 #endif #ifndef __NR_connect #define __NR_connect 42 #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 ? 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 do_sandbox_none(int executor_pid, bool enable_tun) { int pid = fork(); if (pid) return pid; sandbox_common(); loop(); doexit(1); } long r[30]; void* thr(void* arg) { switch ((long)arg) { case 0: r[0] = execute_syscall(__NR_mmap, 0x20000000ul, 0x1f2000ul, 0x3ul, 0x32ul, 0xfffffffffffffffful, 0x0ul, 0, 0, 0); break; case 1: r[1] = execute_syscall(__NR_socket, 0x1aul, 0x2ul, 0x1ul, 0, 0, 0, 0, 0, 0); break; case 2: NONFAILING(*(uint16_t*)0x20000000 = (uint16_t)0x1f); NONFAILING(*(uint8_t*)0x20000002 = (uint8_t)0x8002000004); NONFAILING(*(uint8_t*)0x20000003 = (uint8_t)0x3); NONFAILING(*(uint8_t*)0x20000004 = (uint8_t)0x3); NONFAILING(*(uint8_t*)0x20000005 = (uint8_t)0xfff); NONFAILING(*(uint8_t*)0x20000006 = (uint8_t)0x401); NONFAILING(*(uint8_t*)0x20000007 = (uint8_t)0xef); NONFAILING(*(uint8_t*)0x20000008 = (uint8_t)0x9); r[10] = execute_syscall(__NR_connect, r[1], 0x20000000ul, 0xaul, 0, 0, 0, 0, 0, 0); break; case 3: NONFAILING(*(uint64_t*)0x20003000 = (uint64_t)0x20000000); NONFAILING(*(uint32_t*)0x20003008 = (uint32_t)0x60); NONFAILING(*(uint64_t*)0x20003010 = (uint64_t)0x20008000); NONFAILING(*(uint64_t*)0x20003018 = (uint64_t)0x0); NONFAILING(*(uint64_t*)0x20003020 = (uint64_t)0x20007000); NONFAILING(*(uint64_t*)0x20003028 = (uint64_t)0x10); NONFAILING(*(uint32_t*)0x20003030 = (uint32_t)0x5); NONFAILING(*(uint16_t*)0x20000000 = (uint16_t)0x27); NONFAILING(*(uint32_t*)0x20000004 = (uint32_t)0x0); NONFAILING(*(uint32_t*)0x20000008 = (uint32_t)0x0); NONFAILING(*(uint32_t*)0x2000000c = (uint32_t)0x0); NONFAILING(*(uint8_t*)0x20000010 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x20000011 = (uint8_t)0x0); NONFAILING(memcpy((void*)0x20000012, "\x4e\xa6\xf0\xe3\x26\x38\x41\x0f\x61\xc3\x84\x5a" "\xd3\xe8\x12\x96\xe2\x97\x1a\x49\xc7\x07\x55\xb5" "\x82\x0c\x91\x5b\xe8\xe3\xa2\x1e\x49\x17\x62\x02" "\x27\x36\xcd\x99\x61\x46\xb6\xa2\x93\x9e\xee\x01" "\xc9\xcb\xf2\xeb\x94\x9c\x90\xc2\x85\x56\x30\xea" "\x2a\x71\xf9", 63)); NONFAILING(*(uint64_t*)0x20000058 = (uint64_t)0x0); NONFAILING(*(uint64_t*)0x20007000 = (uint64_t)0x10); NONFAILING(*(uint32_t*)0x20007008 = (uint32_t)0x0); NONFAILING(*(uint32_t*)0x2000700c = (uint32_t)0x0); r[29] = execute_syscall(__NR_sendmsg, r[1], 0x20003000ul, 0x40880ul, 0, 0, 0, 0, 0, 0); break; } return 0; } void loop() { 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(0, false); int status = 0; while (waitpid(pid, &status, __WALL) != pid) { } return 0; }
.config
Description: Binary data
