On Thu, Mar 28, 2019 at 09:25:06AM -0700, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: c10a026b kmsan: use __free_pages() in kmsan_iounmap_page_r.. > git tree: kmsan > console output: https://syzkaller.appspot.com/x/log.txt?x=107d3c7d200000 > kernel config: https://syzkaller.appspot.com/x/.config?x=a5675814e8eae69e > dashboard link: https://syzkaller.appspot.com/bug?extid=86b5c7c236a22616a72f > compiler: clang version 8.0.0 (trunk 350509) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1252834d200000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+86b5c7c236a22616a72f@xxxxxxxxxxxxxxxxxxxxxxxxx > > IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_hsr: link becomes ready > IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready > 8021q: adding VLAN 0 to HW filter on device batadv0 > 8021q: adding VLAN 0 to HW filter on device batadv0 > ================================================================== > BUG: KMSAN: kernel-infoleak in _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32 > CPU: 0 PID: 10131 Comm: syz-executor.4 Not tainted 5.0.0+ #16 > 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+0x173/0x1d0 lib/dump_stack.c:113 > kmsan_report+0x131/0x2a0 mm/kmsan/kmsan.c:636 > kmsan_internal_check_memory+0xaa1/0xbb0 mm/kmsan/kmsan.c:730 > kmsan_copy_to_user+0xab/0xc0 mm/kmsan/kmsan_hooks.c:485 > _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32 > copy_to_user include/linux/uaccess.h:174 [inline] > sctp_getsockopt_peer_addrs net/sctp/socket.c:5911 [inline] > sctp_getsockopt+0x1668e/0x17f70 net/sctp/socket.c:7562 > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2950 > __sys_getsockopt+0x489/0x550 net/socket.c:1938 > __do_sys_getsockopt net/socket.c:1949 [inline] > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1946 > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1946 > do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291 > entry_SYSCALL_64_after_hwframe+0x63/0xe7 > RIP: 0033:0x458209 > Code: ad b8 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 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 > RSP: 002b:00007fdbef191c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037 > RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000458209 > RDX: 000000000000006c RSI: 0000000000000084 RDI: 0000000000000004 > RBP: 000000000073bf00 R08: 0000000020000300 R09: 0000000000000000 > R10: 0000000020000280 R11: 0000000000000246 R12: 00007fdbef1926d4 > R13: 00000000004c96c8 R14: 00000000004d0310 R15: 00000000ffffffff > > Uninit was stored to memory at: > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:205 [inline] > kmsan_save_stack mm/kmsan/kmsan.c:220 [inline] > kmsan_internal_chain_origin+0x134/0x230 mm/kmsan/kmsan.c:426 > kmsan_memcpy_memmove_metadata+0xb5b/0xfe0 mm/kmsan/kmsan.c:304 > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:324 > __msan_memcpy+0x58/0x70 mm/kmsan/kmsan_instr.c:139 > sctp_getsockopt_peer_addrs net/sctp/socket.c:5906 [inline] > sctp_getsockopt+0x16556/0x17f70 net/sctp/socket.c:7562 > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2950 > __sys_getsockopt+0x489/0x550 net/socket.c:1938 > __do_sys_getsockopt net/socket.c:1949 [inline] > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1946 > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1946 > do_syscall_64+0xbc/0xf0 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:205 [inline] > kmsan_save_stack mm/kmsan/kmsan.c:220 [inline] > kmsan_internal_chain_origin+0x134/0x230 mm/kmsan/kmsan.c:426 > kmsan_memcpy_memmove_metadata+0xb5b/0xfe0 mm/kmsan/kmsan.c:304 > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:324 > __msan_memcpy+0x58/0x70 mm/kmsan/kmsan_instr.c:139 > sctp_transport_init net/sctp/transport.c:61 [inline] > sctp_transport_new+0x16d/0x9a0 net/sctp/transport.c:115 > sctp_assoc_add_peer+0x532/0x1f70 net/sctp/associola.c:637 > sctp_process_param net/sctp/sm_make_chunk.c:2548 [inline] > sctp_process_init+0x1a1b/0x3ed0 net/sctp/sm_make_chunk.c:2361 > sctp_cmd_process_init net/sctp/sm_sideeffect.c:682 [inline] > sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1410 [inline] > sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline] > sctp_do_sm+0x3cfc/0x9af0 net/sctp/sm_sideeffect.c:1191 > sctp_assoc_bh_rcv+0x65a/0xd80 net/sctp/associola.c:1074 > sctp_inq_push+0x300/0x420 net/sctp/inqueue.c:95 > sctp_backlog_rcv+0x20a/0xaf0 net/sctp/input.c:354 > sk_backlog_rcv include/net/sock.h:936 [inline] > __release_sock+0x281/0x5f0 net/core/sock.c:2284 > release_sock+0x99/0x2a0 net/core/sock.c:2800 > sctp_wait_for_connect+0x3ee/0x860 net/sctp/socket.c:8751 > sctp_sendmsg_to_asoc+0x2167/0x21a0 net/sctp/socket.c:1967 > sctp_sendmsg+0x3fd7/0x6700 net/sctp/socket.c:2113 > inet_sendmsg+0x54a/0x720 net/ipv4/af_inet.c:798 > sock_sendmsg_nosec net/socket.c:622 [inline] > sock_sendmsg net/socket.c:632 [inline] > ___sys_sendmsg+0xdb9/0x11b0 net/socket.c:2115 > __sys_sendmsg net/socket.c:2153 [inline] > __do_sys_sendmsg net/socket.c:2162 [inline] > __se_sys_sendmsg+0x305/0x460 net/socket.c:2160 > __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2160 > do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291 > entry_SYSCALL_64_after_hwframe+0x63/0xe7 > > Local variable description: ----addr.i@sctp_process_init > Variable was created at: > sctp_process_init+0xb5/0x3ed0 net/sctp/sm_make_chunk.c:2324 > sctp_cmd_process_init net/sctp/sm_sideeffect.c:682 [inline] > sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1410 [inline] > sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline] > sctp_do_sm+0x3cfc/0x9af0 net/sctp/sm_sideeffect.c:1191 > > Bytes 8-15 of 16 are uninitialized > Memory access of size 16 starts at ffff88809511fc28 > Data copied to user address 0000000020000298 > ================================================================== > > > --- > 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#status for how to communicate with syzbot. > syzbot can test patches for this bug, for details see: > https://goo.gl/tpsmEJ#testing-patches > > Hmm, odd. I see where we are doing the copy_to_user call in getsockopt_peer_addrs, but the length we copy should always be equal to or less than what was memcopied to the temp variable. False positive? Neil
