general protection fault in fib6_nh_get_excptn

Kernel	Title	Rank 🛈	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KASAN: slab-out-of-bounds Read in fib6_nh_get_excptn_bucket (3) net	17				2	1529d	1578d	0/29	auto-closed as invalid on 2021/09/13 13:28
Oops: general protection fault, probably for non-canonical address 0xdffffc000000000c: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000060-0x0000000000000067]
CPU: 1 UID: 0 PID: 12331 Comm: syz.0.8241 Not tainted 6.16.0-rc1-syzkaller-00005-g488ef3560196 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:fib6_nh_get_excptn_bucket+0x11f/0x1e0 net/ipv6/route.c:1662
Code: 05 64 74 47 06 01 e8 f0 b8 6e f7 e9 2e ff ff ff e8 66 8b 92 f7 48 8d 7b 60 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 a7 00 00 00 48 8b 5b 60 e8 ce e3 52 01 31 ff 89
RSP: 0018:ffffc900350ef0d8 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90027289000
RDX: 000000000000000c RSI: ffffffff8a28fdaa RDI: 0000000000000060
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000
R13: fffff52006a1de49 R14: 1ffff92006a1de4a R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff888097862000(0063) knlGS:00000000f4ef3b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 000000002f605ff8 CR3: 0000000048097000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 rt6_find_cached_rt+0x151/0x280 net/ipv6/route.c:1860
 ip6_pol_route+0x238/0x1230 net/ipv6/route.c:2275
 pol_lookup_func include/net/ip6_fib.h:617 [inline]
 __fib6_rule_action net/ipv6/fib6_rules.c:237 [inline]
 fib6_rule_action+0x283/0x910 net/ipv6/fib6_rules.c:275
 fib_rules_lookup+0x459/0x1030 net/core/fib_rules.c:339
 fib6_rule_lookup+0x18b/0x720 net/ipv6/fib6_rules.c:112
 ip6_route_output_flags_noref net/ipv6/route.c:2683 [inline]
 ip6_route_output_flags+0x1d0/0x640 net/ipv6/route.c:2695
 ip6_route_output include/net/ip6_route.h:93 [inline]
 ip6_dst_lookup_tail.constprop.0+0xa52/0x2140 net/ipv6/ip6_output.c:1128
 ip6_dst_lookup_flow+0x99/0x1d0 net/ipv6/ip6_output.c:1259
 sctp_v6_get_dst+0x6a2/0x2050 net/sctp/ipv6.c:326
 sctp_transport_route+0x12f/0x350 net/sctp/transport.c:457
 sctp_assoc_add_peer+0x741/0x1550 net/sctp/associola.c:663
 sctp_connect_new_asoc+0x208/0x790 net/sctp/socket.c:1100
 sctp_sendmsg_new_asoc net/sctp/socket.c:1694 [inline]
 sctp_sendmsg+0x15f9/0x1ee0 net/sctp/socket.c:2005
 inet_sendmsg+0x11c/0x140 net/ipv4/af_inet.c:851
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg net/socket.c:727 [inline]
 __sys_sendto+0x43c/0x520 net/socket.c:2180
 __do_sys_sendto net/socket.c:2187 [inline]
 __se_sys_sendto net/socket.c:2183 [inline]
 __ia32_sys_sendto+0xdd/0x1b0 net/socket.c:2183
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0x7c/0x3a0 arch/x86/entry/syscall_32.c:306
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf7fa7579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f4ef355c EFLAGS: 00000296 ORIG_RAX: 0000000000000171
RAX: ffffffffffffffda RBX: 0000000000000008 RCX: 0000000080847fff
RDX: 000000000000fee4 RSI: 0000000000000000 RDI: 000000008005ffe4
RBP: 000000000000001c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:fib6_nh_get_excptn_bucket+0x11f/0x1e0 net/ipv6/route.c:1662
Code: 05 64 74 47 06 01 e8 f0 b8 6e f7 e9 2e ff ff ff e8 66 8b 92 f7 48 8d 7b 60 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 a7 00 00 00 48 8b 5b 60 e8 ce e3 52 01 31 ff 89
RSP: 0018:ffffc900350ef0d8 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90027289000
RDX: 000000000000000c RSI: ffffffff8a28fdaa RDI: 0000000000000060
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000
R13: fffff52006a1de49 R14: 1ffff92006a1de4a R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff888097862000(0063) knlGS:00000000f4ef3b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f741bbe0 CR3: 0000000048097000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
----------------
Code disassembly (best guess), 6 bytes skipped:
   0:	e8 f0 b8 6e f7       	call   0xf76eb8f5
   5:	e9 2e ff ff ff       	jmp    0xffffff38
   a:	e8 66 8b 92 f7       	call   0xf7928b75
   f:	48 8d 7b 60          	lea    0x60(%rbx),%rdi
  13:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  1a:	fc ff df
  1d:	48 89 fa             	mov    %rdi,%rdx
  20:	48 c1 ea 03          	shr    $0x3,%rdx
* 24:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
  28:	0f 85 a7 00 00 00    	jne    0xd5
  2e:	48 8b 5b 60          	mov    0x60(%rbx),%rbx
  32:	e8 ce e3 52 01       	call   0x152e405
  37:	31 ff                	xor    %edi,%edi
  39:	89                   	.byte 0x89