Messages in this thread | | | From | Andrey Konovalov <> | Date | Wed, 8 Feb 2017 20:00:51 +0100 | Subject | net/sctp: null-ptr-deref in sctp_put_port/sctp_endpoint_destroy |
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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.
general protection fault: 0000 [#1] SMP KASAN Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 3 PID: 19506 Comm: syz-executor0 Not tainted 4.10.0-rc7+ #126 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 task: ffff88003d7c1700 task.stack: ffff880037990000 RIP: 0010:__write_once_size include/linux/compiler.h:272 [inline] RIP: 0010:__hlist_del include/linux/list.h:635 [inline] RIP: 0010:__sk_del_bind_node include/net/sock.h:685 [inline] RIP: 0010:__sctp_put_port net/sctp/socket.c:6994 [inline] RIP: 0010:sctp_put_port+0x210/0x620 net/sctp/socket.c:7004 RSP: 0018:ffff8800379969e0 EFLAGS: 00010246 RAX: dffffc0000000010 RBX: 1ffff10006f32d41 RCX: ffff880037996a28 RDX: 0000000000000000 RSI: 0000000000000000 RDI: dffffc0000000000 RBP: ffff880037996b10 R08: 0000000000000000 R09: 0000000000000000 R10: 1c8b9dfca637effe R11: dffffc0000000000 R12: 0000000000000005 R13: ffff880037996ae8 R14: ffff88003a066c40 R15: ffff88003a067178 FS: 00007fd314dba700(0000) GS:ffff88006df00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020002ffc CR3: 000000003b10e000 CR4: 00000000000006e0 Call Trace: sctp_endpoint_destroy net/sctp/endpointola.c:275 [inline] sctp_endpoint_put+0x1b2/0x260 net/sctp/endpointola.c:296 sctp_endpoint_free+0x97/0xc0 net/sctp/endpointola.c:238 sctp_destroy_sock+0xd6/0x470 net/sctp/socket.c:4254 sctp_v6_destroy_sock+0x15/0x20 net/sctp/socket.c:7871 sk_common_release+0xbf/0x4e0 net/core/sock.c:2747 sctp_close+0x764/0x9f0 net/sctp/socket.c:1550 inet_release+0xed/0x1c0 net/ipv4/af_inet.c:425 inet6_release+0x50/0x70 net/ipv6/af_inet6.c:431 sock_release+0x8d/0x1e0 net/socket.c:599 sock_close+0x16/0x20 net/socket.c:1063 __fput+0x332/0x7f0 fs/file_table.c:208 ____fput+0x15/0x20 fs/file_table.c:244 task_work_run+0x19b/0x270 kernel/task_work.c:116 exit_task_work include/linux/task_work.h:21 [inline] do_exit+0x186b/0x2800 kernel/exit.c:839 do_group_exit+0x149/0x420 kernel/exit.c:943 get_signal+0x76d/0x17e0 kernel/signal.c:2313 do_signal+0xd2/0x2190 arch/x86/kernel/signal.c:807 exit_to_usermode_loop+0x170/0x200 arch/x86/entry/common.c:156 prepare_exit_to_usermode arch/x86/entry/common.c:190 [inline] syscall_return_slowpath+0x3d3/0x420 arch/x86/entry/common.c:259 entry_SYSCALL_64_fastpath+0xc0/0xc2 RIP: 0033:0x4458b9 RSP: 002b:00007fd314db9cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 0000000000708170 RCX: 00000000004458b9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000708170 RBP: 0000000000708150 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007fd314dba9c0 R15: 00007fd314dba700 Code: ff ff ff 49 8b 76 20 48 bf 00 00 00 00 00 fc ff df 49 89 c8 49 c1 e8 03 41 c6 04 38 00 49 89 f0 49 89 95 40 ff ff ff 49 c1 e8 03 <41> 80 3c 38 00 0f 85 f6 02 00 00 48 c1 e9 03 49 b8 00 00 00 00 RIP: __write_once_size include/linux/compiler.h:272 [inline] RSP: ffff8800379969e0 RIP: __hlist_del include/linux/list.h:635 [inline] RSP: ffff8800379969e0 RIP: __sk_del_bind_node include/net/sock.h:685 [inline] RSP: ffff8800379969e0 RIP: __sctp_put_port net/sctp/socket.c:6994 [inline] RSP: ffff8800379969e0 RIP: sctp_put_port+0x210/0x620 net/sctp/socket.c:7004 RSP: ffff8800379969e0 ---[ end trace 54c316f8731a5a88 ]--- Kernel panic - not syncing: Fatal exception in interrupt Dumping ftrace buffer: (ftrace buffer empty) Kernel Offset: disabled Rebooting in 86400 seconds.. [unhandled content-type:application/octet-stream]// 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_setsockopt #define __NR_setsockopt 54 #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[4]; void loop() { memset(r, -1, sizeof(r)); r[0] = execute_syscall(__NR_mmap, 0x20000000ul, 0xef0000ul, 0x3ul, 0x32ul, 0xfffffffffffffffful, 0x0ul, 0, 0, 0); r[1] = execute_syscall(__NR_socket, 0xaul, 0x5ul, 0x84ul, 0, 0, 0, 0, 0, 0); NONFAILING(*(uint32_t*)0x2051d000 = (uint32_t)0x5); r[3] = execute_syscall(__NR_setsockopt, r[1], 0x29ul, 0xd1ul, 0x2051d000ul, 0x4ul, 0, 0, 0, 0); } int main() { setup_main_process(); int pid = do_sandbox_none(0, false); int status = 0; while (waitpid(pid, &status, __WALL) != pid) { } return 0; }
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