On Thu, Dec 06, 2018 at 11:36:08AM +0100, Alexander Potapenko wrote: > On Wed, Dec 5, 2018 at 8:31 PM syzbot > <syzbot+ad5d327e6936a2e284be@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > > Hello, > > > > syzbot found the following crash on: > > > > HEAD commit: fffec98ae2a6 net: proper support for CONFIG_GENERIC_CSUM o.. > > git tree: https://github.com/google/kmsan.git/master > > console output: https://syzkaller.appspot.com/x/log.txt?x=12e84a47400000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=56b48b46dafe4516 > > dashboard link: https://syzkaller.appspot.com/bug?extid=ad5d327e6936a2e284be > > compiler: clang version 8.0.0 (trunk 343298) > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=103cd225400000 > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > Reported-by: syzbot+ad5d327e6936a2e284be@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > 8021q: adding VLAN 0 to HW filter on device team0 > > 8021q: adding VLAN 0 to HW filter on device team0 > > 8021q: adding VLAN 0 to HW filter on device team0 > > 8021q: adding VLAN 0 to HW filter on device team0 > > ================================================================== > > BUG: KMSAN: kernel-infoleak in _copy_to_user+0x19a/0x230 lib/usercopy.c:33 > > CPU: 1 PID: 8164 Comm: syz-executor2 Not tainted 4.20.0-rc3+ #95 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > > Google 01/01/2011 > > Call Trace: > > __dump_stack lib/dump_stack.c:77 [inline] > > dump_stack+0x32d/0x480 lib/dump_stack.c:113 > > kmsan_report+0x12c/0x290 mm/kmsan/kmsan.c:683 > > kmsan_internal_check_memory+0x32a/0xa50 mm/kmsan/kmsan.c:743 > > kmsan_copy_to_user+0x78/0xd0 mm/kmsan/kmsan_hooks.c:634 > > _copy_to_user+0x19a/0x230 lib/usercopy.c:33 > > copy_to_user include/linux/uaccess.h:183 [inline] > > sctp_getsockopt_local_addrs net/sctp/socket.c:5998 [inline] > > sctp_getsockopt+0x15248/0x186f0 net/sctp/socket.c:7477 > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937 > > __sys_getsockopt+0x489/0x550 net/socket.c:1939 > > __do_sys_getsockopt net/socket.c:1950 [inline] > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947 > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947 > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291 > > entry_SYSCALL_64_after_hwframe+0x63/0xe7 > > RIP: 0033:0x457569 > > Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 > > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff > > ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 > > RSP: 002b:00007f4991886c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037 > > RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000457569 > > RDX: 000000000000006d RSI: 0000000000000084 RDI: 0000000000000003 > > RBP: 000000000072bf00 R08: 0000000020000140 R09: 0000000000000000 > > R10: 0000000020001100 R11: 0000000000000246 R12: 00007f49918876d4 > > R13: 00000000004c7d88 R14: 00000000004ce348 R15: 00000000ffffffff > > > > Uninit was stored to memory at: > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline] > > kmsan_save_stack mm/kmsan/kmsan.c:261 [inline] > > kmsan_internal_chain_origin+0x13d/0x240 mm/kmsan/kmsan.c:469 > > kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:344 > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:362 > > __msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:162 > > sctp_copy_laddrs net/sctp/socket.c:5901 [inline] > > sctp_getsockopt_local_addrs net/sctp/socket.c:5967 [inline] > > sctp_getsockopt+0x14f41/0x186f0 net/sctp/socket.c:7477 > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937 > > __sys_getsockopt+0x489/0x550 net/socket.c:1939 > > __do_sys_getsockopt net/socket.c:1950 [inline] > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947 > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947 > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291 > > entry_SYSCALL_64_after_hwframe+0x63/0xe7 > > > > Uninit was stored to memory at: > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline] > > kmsan_save_stack mm/kmsan/kmsan.c:261 [inline] > > kmsan_internal_chain_origin+0x13d/0x240 mm/kmsan/kmsan.c:469 > > kmsan_memcpy_memmove_metadata+0x1a9/0xf70 mm/kmsan/kmsan.c:344 > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:362 > > __msan_memcpy+0x61/0x70 mm/kmsan/kmsan_instr.c:162 > > sctp_copy_laddrs net/sctp/socket.c:5890 [inline] > > sctp_getsockopt_local_addrs net/sctp/socket.c:5967 [inline] > > sctp_getsockopt+0x14de8/0x186f0 net/sctp/socket.c:7477 > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937 > > __sys_getsockopt+0x489/0x550 net/socket.c:1939 > > __do_sys_getsockopt net/socket.c:1950 [inline] > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947 > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947 > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291 > > entry_SYSCALL_64_after_hwframe+0x63/0xe7 > > > > Uninit was created at: > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:246 [inline] > > kmsan_internal_poison_shadow+0x6d/0x130 mm/kmsan/kmsan.c:170 > > kmsan_kmalloc+0xa1/0x100 mm/kmsan/kmsan_hooks.c:186 > > __kmalloc+0x14c/0x4d0 mm/slub.c:3825 > > kmalloc include/linux/slab.h:551 [inline] > > sctp_inet6addr_event+0x60e/0xbd0 net/sctp/ipv6.c:100 > > notifier_call_chain kernel/notifier.c:93 [inline] > > __atomic_notifier_call_chain kernel/notifier.c:183 [inline] > > atomic_notifier_call_chain+0x13d/0x240 kernel/notifier.c:193 > > inet6addr_notifier_call_chain+0x76/0x90 net/ipv6/addrconf_core.c:107 > > ipv6_add_addr+0x2597/0x2890 net/ipv6/addrconf.c:1115 > > inet6_addr_add+0xc86/0x1c10 net/ipv6/addrconf.c:2912 > > inet6_rtm_newaddr+0x167e/0x3d20 net/ipv6/addrconf.c:4750 > > rtnetlink_rcv_msg+0x1148/0x1540 net/core/rtnetlink.c:4947 > > netlink_rcv_skb+0x394/0x640 net/netlink/af_netlink.c:2477 > > rtnetlink_rcv+0x50/0x60 net/core/rtnetlink.c:4965 > > netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline] > > netlink_unicast+0x1699/0x1740 net/netlink/af_netlink.c:1336 > > netlink_sendmsg+0x13c7/0x1440 net/netlink/af_netlink.c:1917 > > sock_sendmsg_nosec net/socket.c:621 [inline] > > sock_sendmsg net/socket.c:631 [inline] > > ___sys_sendmsg+0xe3b/0x1240 net/socket.c:2116 > > __sys_sendmsg net/socket.c:2154 [inline] > > __do_sys_sendmsg net/socket.c:2163 [inline] > > __se_sys_sendmsg+0x305/0x460 net/socket.c:2161 > > __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2161 > > do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291 > > entry_SYSCALL_64_after_hwframe+0x63/0xe7 > > > > Bytes 32-35 of 2100 are uninitialized > > Memory access of size 2100 starts at ffff888185d8b000 > > Data copied to user address 0000000020001108 > > ================================================================== > When a network device goes up and sctp_inetaddr_event() is called, it > allocates a partially initialized struct sctp_sockaddr_entry to hold > the newly created address. > The attached reproducer can be then used to read up to 8 uninit bytes > for each of the local addresses. > I guess the devices aren't created so often that this can pose any > security risk, but we probably still need to allocate this structure > with __GFP_ZERO. Agree. Thanks Alexander. Looks like this is the last/only place left with this issue. > > > > --- > > This bug is generated by a bot. It may contain errors. > > See https://goo.gl/tpsmEJ for more information about syzbot. > > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > > > > syzbot will keep track of this bug report. See: > > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with > > syzbot. > > syzbot can test patches for this bug, for details see: > > https://goo.gl/tpsmEJ#testing-patches > > > > -- > > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group. > > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@xxxxxxxxxxxxxxxx. > > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/000000000000311344057c4b6cc3%40google.com. > > For more options, visit https://groups.google.com/d/optout. > > > > -- > Alexander Potapenko > Software Engineer > > Google Germany GmbH > Erika-Mann-Straße, 33 > 80636 München > > Geschäftsführer: Paul Manicle, Halimah DeLaine Prado > Registergericht und -nummer: Hamburg, HRB 86891 > Sitz der Gesellschaft: Hamburg > #ifndef DUMP_BUF_H > #define DUMP_BUF_H > > #ifndef DUMP_MIN_STRLEN > #define DUMP_MIN_STRLEN 1 > #endif > > #ifndef DUMP_PARALLEL > #define DUMP_PARALLEL 0 > #endif > > #ifndef DUMP_PRINT_BUF_ADDR > #define DUMP_PRINT_BUF_ADDR 0 > #endif > > #ifndef DUMP_PRINT_HEX > #define DUMP_PRINT_HEX 0 > #endif > > #ifndef DUMP_PRINT_STRING > #define DUMP_PRINT_STRING 0 > #endif > > #if DUMP_PARALLEL > pthread_mutex_t out_mutex = PTHREAD_MUTEX_INITIALIZER; > #endif > > void dump_buf(unsigned char *buf, int len) { > int i, nz = 0; > for (i = 0; i < len; i++) { > if (buf[i]) { > nz = 1; > break; > } > } > if (!nz) { > // The buffer is empty. > return; > } else { > #if DUMP_PARALLEL > pthread_mutex_lock(&out_mutex); > #endif > #if DUMP_PRINT_BUF_ADDR > fprintf(stderr, "nonempty buffer at %p\n", buf); > #endif > #if DUMP_PRINT_HEX > for (i=0; i < len; i++) { > if (buf[i]) { > fprintf(stderr, "buf[%d]: %x (%p)\n", i, buf[i], *(void**)&buf[i]); > } > } > #endif // DUMP_PRINT_HEX > #if DUMP_PARALLEL > pthread_mutex_unlock(&out_mutex); > #endif > } > #if DUMP_PARALLEL > pthread_mutex_lock(&out_mutex); > #endif > #if DUMP_PRINT_STRING > for (i = 0; i < len; i++) { > if (buf[i]) { > int str_len = strlen(&buf[i]); > // Short string pieces are too boring. > if (str_len >= DUMP_MIN_STRLEN) { > unsigned char *c; > for (c = &buf[i]; c < &buf[i + str_len]; c++) { > if ((*c > 127) || ((*c < 32) && (*c != 10) && (*c != 13))) { > *c = ' '; > continue; > } > } > // Dump the buffer. > fprintf(stderr, "%s\n", &buf[i]); > } > i += str_len; > } > } > #endif // DUMP_PRINT_STRING > #if DUMP_PARALLEL > pthread_mutex_unlock(&out_mutex); > #endif > } > > #endif > #include <stdio.h> > #include <pthread.h> > #include <sys/types.h> /* See NOTES */ > #include <sys/socket.h> > #include <unistd.h> > > #define DUMP_PARALLEL 1 > #define DUMP_PRINT_BUF_ADDR 1 > #define DUMP_PRINT_STRING 1 > #define DUMP_PRINT_HEX 1 > #include "dump_buf.h" > > void *setsockopt_fn(void *arg) { > int sock = (int)arg; > struct sockaddr addr; > memset(&addr, 0, sizeof(addr)); > addr.sa_family = 2; > addr.sa_data[2] = 0xac; > addr.sa_data[3] = 0x14; > addr.sa_data[4] = 0x14; > setsockopt(sock, 0x84, 0x6e, &addr, 0x10); > } > > #define BUFLEN (0x2c2) > void *getsockopt_fn(void *arg) { > int sock = (int)arg; > char buf[BUFLEN]; > memset(buf, 0, BUFLEN); > int socklen = BUFLEN; > getsockopt(sock, 0x84, /*SCTP_GET_LOCAL_ADDRS*/0x6d, buf, &socklen); > dump_buf(&(buf[8]), 32); > } > > void do_work(int sock) { > pthread_t t1, t2; > for (int i = 0; i < 10; i++) { > pthread_create(&t1, NULL, getsockopt_fn, (void*)sock); > pthread_create(&t2, NULL, setsockopt_fn, (void*)sock); > usleep(100); > } > } > > int main(int argc, char *argv[]) { > int res; > int pid = fork(); > if (pid == 0) { > int sock = socket(0x2, 0x1, 0x84); > do_work(sock); > } > sleep(10); > return 0; > }
