Messages in this thread | | | From | Andrey Konovalov <> | Date | Thu, 9 Feb 2017 13:28:08 +0100 | Subject | net/ipv4: null-ptr-deref in udp_rmem_release/sk_memory_allocated_sub |
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Hi,
I've got the following error report while fuzzing the kernel with syzkaller.
On commit 926af6273fc683cd98cd0ce7bf0d04a02eed6742.
A reproducer and .config are attached.
BUG: unable to handle kernel NULL pointer dereference at (null) IP: sk_memory_allocated_sub include/net/sock.h:1214 [inline] IP: __sk_mem_reduce_allocated+0xa9/0x390 net/core/sock.c:2215 PGD 3aa86067 PUD 33243067 PMD 0
Oops: 0002 [#1] SMP KASAN Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 3 PID: 13215 Comm: syz-executor5 Not tainted 4.10.0-rc7+ #126 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 task: ffff88006bf59700 task.stack: ffff88005e0a8000 RIP: 0010:sk_memory_allocated_sub include/net/sock.h:1214 [inline] RIP: 0010:__sk_mem_reduce_allocated+0xa9/0x390 net/core/sock.c:2215 RSP: 0018:ffff88005e0afa48 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 1ffff1000bc15f4a RCX: 1ffffffff0bc7d8e RDX: dffffc0000000000 RSI: ffffffff83343399 RDI: ffffffff85e3ec70 RBP: ffff88005e0afad8 R08: 0000000000000090 R09: 0000000000000000 R10: 0000000000000002 R11: 0000000000000000 R12: ffff88003dfb3c40 R13: 000000000003dfb4 R14: ffff88003dfb3c68 R15: ffffffff85e3eba0 FS: 00007f71b9ba9700(0000) GS:ffff88006df00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000000393b8000 CR4: 00000000000006e0 Call Trace: udp_rmem_release+0x14f/0x180 net/ipv4/udp.c:1199 first_packet_length+0x215/0x6e0 net/ipv4/udp.c:1380 udp_ioctl+0x13f/0x2c0 net/ipv4/udp.c:1401 inet6_ioctl+0x19e/0x1e0 net/ipv6/af_inet6.c:530 sock_do_ioctl+0x65/0xb0 net/socket.c:897 sock_ioctl+0x28f/0x440 net/socket.c:995 vfs_ioctl fs/ioctl.c:43 [inline] do_vfs_ioctl+0x1bf/0x1780 fs/ioctl.c:683 SYSC_ioctl fs/ioctl.c:698 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:689 entry_SYSCALL_64_fastpath+0x1f/0xc2 RIP: 0033:0x4458b9 RSP: 002b:00007f71b9ba8b58 EFLAGS: 00000286 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00000000004458b9 RDX: 0000000020005f3e RSI: 000000000000541b RDI: 0000000000000005 RBP: 00000000006e0cc0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000286 R12: 00000000007080a8 R13: 0000000000000000 R14: 00007f71b9ba99c0 R15: 00007f71b9ba9700 Code: 24 28 48 ba 00 00 00 00 00 fc ff df 49 8d bf d0 00 00 00 48 89 f9 48 c1 e9 03 80 3c 11 00 0f 85 8b 02 00 00 49 8b 87 d0 00 00 00 <f0> 4c 29 28 4d 8b 7c 24 28 48 ba 00 00 00 00 00 fc ff df 49 8d RIP: sk_memory_allocated_sub include/net/sock.h:1214 [inline] RSP: ffff88005e0afa48 RIP: __sk_mem_reduce_allocated+0xa9/0x390 net/core/sock.c:2215 RSP: ffff88005e0afa48 CR2: 0000000000000000 ---[ end trace 8b75e9ae315695b0 ]--- 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_ioctl #define __NR_ioctl 16 #endif #ifndef __NR_bind #define __NR_bind 49 #endif #ifndef __NR_connect #define __NR_connect 42 #endif #ifndef __NR_sendto #define __NR_sendto 44 #endif #ifndef __NR_mmap #define __NR_mmap 9 #endif #ifndef __NR_socket #define __NR_socket 41 #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[19]; void* thr(void* arg) { switch ((long)arg) { case 0: r[0] = execute_syscall(__NR_mmap, 0x20000000ul, 0x987000ul, 0x3ul, 0x32ul, 0xfffffffffffffffful, 0x0ul, 0, 0, 0); break; case 1: r[1] = execute_syscall(__NR_socket, 0xaul, 0x2ul, 0x73ul, 0, 0, 0, 0, 0, 0); break; case 2: r[2] = execute_syscall(__NR_ioctl, r[1], 0x541bul, 0x20005f3eul, 0, 0, 0, 0, 0, 0); break; case 3: NONFAILING(*(uint16_t*)0x20000fe0 = (uint16_t)0xa); NONFAILING(*(uint16_t*)0x20000fe2 = (uint16_t)0x234e); NONFAILING(*(uint32_t*)0x20000fe4 = (uint32_t)0x20000000000000); NONFAILING(*(uint64_t*)0x20000fe8 = (uint64_t)0x0); NONFAILING(*(uint64_t*)0x20000ff0 = (uint64_t)0x100000000000000); NONFAILING(*(uint32_t*)0x20000ff8 = (uint32_t)0x1); r[9] = execute_syscall(__NR_bind, r[1], 0x20000fe0ul, 0x20ul, 0, 0, 0, 0, 0, 0); break; case 4: NONFAILING(*(uint16_t*)0x20000000 = (uint16_t)0xa); NONFAILING(*(uint16_t*)0x20000002 = (uint16_t)0x204e); NONFAILING(*(uint32_t*)0x20000004 = (uint32_t)0xfd4); NONFAILING(*(uint64_t*)0x20000008 = (uint64_t)0x0); NONFAILING(*(uint64_t*)0x20000010 = (uint64_t)0x0); NONFAILING(*(uint32_t*)0x20000018 = (uint32_t)0x5); r[16] = execute_syscall(__NR_connect, r[1], 0x20000000ul, 0x20ul, 0, 0, 0, 0, 0, 0); break; case 5: NONFAILING(memcpy( (void*)0x20003f3f, "\xc9\x00\x00\x00\x00\x00\x00\x00\x00\x14\xf7\xa4\x1c\x95\x84" "\x6e\xac\xb3\xee\x27\xb4\x75\x68\xc5\x83\x6b\xb8\x94\x1e\x43" "\x8c\x9a\x7b\x37\x8a\xb5\xfb\xf7\x1e\x8a\xc8\x36\xca\xf8\x82" "\x4a\xc0\x76\x79\x35\x52\xec\x17\xcc\x77\xb2\xbb\x79\x41\x1a" "\xae\x8c\x23\x52\xa8\x8d\x17\x90\x37\x6e\xb1\xdd\x72\x03\xa2" "\x70\xa3\xc3\xd3\x84\xe6\xd3\x75\x95\xf4\x34\x30\x93\x0c\x0c" "\x3b\x39\x15\x7b\x30\x4a\x44\xb1\x4c\x54\xec\x64\xf4\xc6\x71" "\x73\x4e\x00\x9e\x23\xcf\xf8\x15\xcc\xbe\x36\x31\x5c\x92\x19" "\x71\x8d\xe7\x2c\xaa\x3f\xbf\x08\xe6\x68\xaa\x28\x37\x0f\xee" "\x68\xfa\xa1\xa8\xda\x01\xcd\x29\x28\xb3\xb7\x77\x04\x6b\x57" "\xa9\x8f\xad\xb5\xf6\x3a\x82\xbb\x62\x9a\xe3\x07\x83\xde\xbc" "\x23\x11\x29\x7f\x52\x2b\x6d\x6e\x78\x38\x6e\x49\x20\xbe\x61" "\xfe\xeb\x81\x04\x00\x00\x00\x00\x00\x00\xae\x05\xd9", 193)); r[18] = execute_syscall(__NR_sendto, r[1], 0x20003f3ful, 0xc1ul, 0x4ul, 0x0ul, 0x0ul, 0, 0, 0); break; } return 0; }
void loop() { long i; pthread_t th[12];
memset(r, -1, sizeof(r)); srand(getpid()); for (i = 0; i < 6; i++) { pthread_create(&th[i], 0, thr, (void*)i); usleep(10000); } for (i = 0; i < 6; i++) { pthread_create(&th[6 + 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; } [unhandled content-type:application/octet-stream] | |