+a...@redhat.com Hi,
I've got the following error report while running the syzkaller fuzzer: kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] SMP KASAN Modules linked in: CPU: 0 PID: 3953 Comm: syz-executor Not tainted 4.9.0-rc1+ #228 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 task: ffff88006aa2ac00 task.stack: ffff880068a90000 RIP: 0010:[<ffffffff834ed8f4>] [<ffffffff834ed8f4>] ipxrtr_route_packet+0x4e4/0xbe0 net/ipx/ipx_route.c :213 RSP: 0018:ffff880068a97b08 EFLAGS: 00010246 RAX: ffff88006b648500 RBX: ffff880068a97e40 RCX: dffffc0000000000 RDX: 0000000000000003 RSI: 0000000000000000 RDI: ffff88006b648960 RBP: ffff880068a97bc8 R08: dffffc0000000000 R09: 1ffff1000d4ddf97 R10: dffffc0000000000 R11: 0000000000000000 R12: ffff88006b410300 R13: 0000000000000000 R14: ffff88006444b68e R15: ffff88006a6efc80 FS: 00007f28cf665700(0000) GS:ffff88006cc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000451f80 CR3: 0000000068a9a000 CR4: 00000000000006f0 Stack: ffff88006a6efd58 ffff880068a97dc0 ffff880068a97e44 1ffff1000d152f68 000000000000001a 0000000000000000 ffff88006b648500 0000000041b58ab3 ffffffff847fb90b ffffffff834ed410 ffffffff82b7cfea ffff8800ffffff97 Call Trace: [<ffffffff834e802e>] ipx_sendmsg+0x30e/0x550 net/ipx/af_ipx.c:1749 [< inline >] sock_sendmsg_nosec net/socket.c:606 [<ffffffff82b7075c>] sock_sendmsg+0xcc/0x110 net/socket.c:616 [<ffffffff82b718a1>] SYSC_sendto+0x211/0x340 net/socket.c:1641 [<ffffffff82b73e80>] SyS_sendto+0x40/0x50 net/socket.c:1609 [<ffffffff83fc0141>] entry_SYSCALL_64_fastpath+0x1f/0xc2 arch/x86/entry/entry_64.S:209 Code: 41 80 7c 0d 00 00 0f 85 82 06 00 00 48 8b 85 70 ff ff ff 49 b8 00 00 00 00 00 fc ff df 4c 8b a8 60 04 00 00 4c 89 ee 48 c1 ee 03 <46> 0f b6 0c 06 45 84 c9 74 0a 41 80 f9 03 0f 8e e5 05 00 00 49 RIP [<ffffffff834ed8f4>] ipxrtr_route_packet+0x4e4/0xbe0 net/ipx/ipx_route.c:213 RSP <ffff880068a97b08> ---[ end trace f5bc9a28de6b2776 ]--- ================================================================== For some reason ipxs->intrfc ends up being NULL. The reproducer is attached, you need to run a few instances simultaneously. In case it's relevant, this is what I have in /etc/network/interfaces: auto eth1 iface eth1 inet static address 192.168.1.5 netmask 255.255.255.0 post-up arp -s 192.168.1.6 aa:aa:aa:aa:aa:aa iface eth1 ipx static frame EtherII netnum 0x42424242 On commit 1a1891d762d6e64daf07b5be4817e3fbb29e3c59 (Oct 18).
// autogenerated by syzkaller (http://github.com/google/syzkaller) #ifndef __NR_sendto #define __NR_sendto 44 #endif #ifndef __NR_syz_fuse_mount #define __NR_syz_fuse_mount 1000004 #endif #ifndef __NR_syz_open_dev #define __NR_syz_open_dev 1000002 #endif #ifndef __NR_syz_test #define __NR_syz_test 1000001 #endif #ifndef __NR_mmap #define __NR_mmap 9 #endif #ifndef __NR_socket #define __NR_socket 41 #endif #ifndef __NR_bind #define __NR_bind 49 #endif #ifndef __NR_syz_fuseblk_mount #define __NR_syz_fuseblk_mount 1000005 #endif #ifndef __NR_syz_open_pts #define __NR_syz_open_pts 1000003 #endif #include <fcntl.h> #include <pthread.h> #include <setjmp.h> #include <signal.h> #include <stddef.h> #include <stdint.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/ioctl.h> #include <sys/stat.h> #include <sys/syscall.h> #include <sys/types.h> #include <unistd.h> __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); } } long r[18]; int main() { install_segv_handler(); memset(r, -1, sizeof(r)); r[0] = execute_syscall(__NR_mmap, 0x20000000ul, 0xe000ul, 0x3ul, 0x32ul, 0xfffffffffffffffful, 0x0ul, 0, 0, 0); r[1] = execute_syscall(__NR_socket, 0x4ul, 0x2ul, 0x0ul, 0, 0, 0, 0, 0, 0); r[2] = execute_syscall(__NR_mmap, 0x2000e000ul, 0x1000ul, 0x3ul, 0x32ul, 0xfffffffffffffffful, 0x0ul, 0, 0, 0); NONFAILING(*(uint16_t*)0x2000e000 = (uint16_t)0x2); NONFAILING(*(uint16_t*)0x2000e002 = (uint16_t)0x4242); NONFAILING(*(uint32_t*)0x2000e004 = (uint32_t)0x0); NONFAILING(*(uint8_t*)0x2000e008 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x2000e009 = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x2000e00a = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x2000e00b = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x2000e00c = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x2000e00d = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x2000e00e = (uint8_t)0x0); NONFAILING(*(uint8_t*)0x2000e00f = (uint8_t)0x0); r[14] = execute_syscall(__NR_bind, r[1], 0x2000e000ul, 0x10ul, 0, 0, 0, 0, 0, 0); NONFAILING(memcpy((void*)0x20007fe6, "\xae\x89\xfa\x41\xd0\x29\x69" "\xc3\xac\x79\xf0\x64\xc6\xad" "\x6b\x27\x63\x6b\x49\x0d\x99" "\x7b\x01\x9e\x3e\xb3", 26)); NONFAILING(memcpy( (void*)0x2000d000, "\x04\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" "\x00", 128)); r[17] = execute_syscall(__NR_sendto, r[1], 0x20007fe6ul, 0x1aul, 0x0ul, 0x2000d000ul, 0x80ul, 0, 0, 0); return 0; }
