1TITLE: BUG: bad usercopy in sctp_getsockopt 2 3syzkaller login: [ 55.288565] usercopy: kernel memory exposure attempt detected from ffff8801d4310630 (SCTPv6) (11 bytes) 4[ 55.290089] ------------[ cut here ]------------ 5[ 55.290728] kernel BUG at mm/usercopy.c:84! 6[ 55.291539] invalid opcode: 0000 [#1] SMP KASAN 7[ 55.292183] Dumping ftrace buffer: 8[ 55.292677] (ftrace buffer empty) 9[ 55.293174] Modules linked in: 10[ 55.293614] CPU: 1 PID: 2993 Comm: syzkaller447333 Not tainted 4.14.0-rc5-mm1+ #20 11[ 55.294640] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 12[ 55.295862] task: ffff8801d1cb8740 task.stack: ffff8801d2210000 13[ 55.296668] RIP: 0010:__check_object_size+0x3a2/0x4f0 14[ 55.297366] RSP: 0018:ffff8801d22170f0 EFLAGS: 00010286 15[ 55.298076] RAX: 000000000000005b RBX: ffffffff8511a180 RCX: 0000000000000000 16[ 55.299057] RDX: 000000000000005b RSI: 1ffff1003a442dde RDI: ffffed003a442e12 17[ 55.300010] RBP: ffff8801d22171e0 R08: 0000000000000001 R09: 0000000000000000 18[ 55.300975] R10: ffff8801d2217098 R11: 0000000000000000 R12: ffffffff8511a140 19[ 55.301926] R13: ffff8801d4310630 R14: 000000000000000b R15: ffffea000750c400 20[ 55.302941] FS: 0000000002000880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 21[ 55.304015] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 22[ 55.304830] CR2: 0000000020673000 CR3: 00000001d223e000 CR4: 00000000001406e0 23[ 55.305805] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 24[ 55.306773] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 25[ 55.307725] Call Trace: 26[ 55.308085] ? lock_release+0xa40/0xa40 27[ 55.308636] ? check_stack_object+0x140/0x140 28[ 55.309236] ? __local_bh_enable_ip+0x9d/0x160 29[ 55.313787] ? __might_sleep+0x95/0x190 30[ 55.317730] sctp_getsockopt+0x2b90/0x70b0 31[ 55.321930] ? do_raw_spin_trylock+0x190/0x190 32[ 55.644961] sock_common_getsockopt+0x95/0xd0 33[ 55.649423] ? sock_common_getsockopt+0x95/0xd0 34[ 55.654064] SyS_getsockopt+0x178/0x340 35[ 55.658011] ? SyS_setsockopt+0x360/0x360 36[ 55.677058] entry_SYSCALL_64_fastpath+0x1f/0xbe 37[ 55.681780] RIP: 0033:0x43fc99 38[ 55.684936] RSP: 002b:00007ffd542b5808 EFLAGS: 00000203 ORIG_RAX: 0000000000000037 39[ 55.692609] RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fc99 40[ 55.699845] RDX: 000000000000000b RSI: 0000000000000084 RDI: 0000000000000003 41[ 55.707079] RBP: 0000000000000082 R08: 0000000020673000 R09: 0000000000000000 42[ 55.714313] R10: 0000000020cd1000 R11: 0000000000000203 R12: 0000000000401600 43[ 55.721547] R13: 0000000000401690 R14: 0000000000000000 R15: 0000000000000000 44[ 55.728790] Code: 48 0f 44 da e8 e0 d7 c3 ff 48 8b 85 28 ff ff ff 4d 89 f1 4c 89 e9 4c 89 e2 48 89 de 48 c7 c7 c0 a1 11 85 49 89 c0 e8 33 e3 ad ff <0f> 0b 48 c7 c0 80 9f 11 85 eb 96 48 c7 c0 c0 9f 11 85 eb 8d 48 45[ 55.747858] RIP: __check_object_size+0x3a2/0x4f0 RSP: ffff8801d22170f0 46[ 55.754590] ---[ end trace 569becb7b442ce27 ]--- 47[ 55.759474] Kernel panic - not syncing: Fatal exception 48[ 55.764842] Dumping ftrace buffer: 49[ 55.768350] (ftrace buffer empty) 50[ 55.772032] Kernel Offset: disabled 51[ 55.775627] Rebooting in 86400 seconds. 52