[syzbot] [net?] general protection fault in ip6_pol_route (3)

From: syzbot
Date: Tue Feb 04 2025 - 09:10:43 EST

Hello,

syzbot found the following issue on:

HEAD commit: f1b785f4c787 Merge tag 'for_linus' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=100bc1a7980000
kernel config: https://syzkaller.appspot.com/x/.config?x=d2aeec8c0b2e420c
dashboard link: https://syzkaller.appspot.com/bug?extid=3201be560ebfa39bc6bd
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1209e4c0580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-f1b785f4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3d6bd514fd25/vmlinux-f1b785f4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/bf9273b213e1/bzImage-f1b785f4.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/d332161a8efa/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3201be560ebfa39bc6bd@xxxxxxxxxxxxxxxxxxxxxxxxx

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000013: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000098-0x000000000000009f]
CPU: 0 UID: 0 PID: 24 Comm: kworker/u4:2 Not tainted 6.12.0-rc7-syzkaller-00042-gf1b785f4c787 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: events_unbound macvlan_process_broadcast
RIP: 0010:rt6_get_pcpu_route net/ipv6/route.c:1408 [inline]
RIP: 0010:ip6_pol_route+0x4d1/0x15d0 net/ipv6/route.c:2264
Code: 93 f7 48 8b 03 65 4c 8b 30 31 ff 4c 89 f6 e8 86 b4 29 f7 4d 85 f6 0f 84 da 00 00 00 49 8d 9e 98 00 00 00 48 89 d8 48 c1 e8 03 <42> 0f b6 04 38 84 c0 0f 85 12 0f 00 00 44 8b 3b 31 ff 44 89 fe e8
RSP: 0018:ffffc900000073a0 EFLAGS: 00010202
RAX: 0000000000000013 RBX: 0000000000000099 RCX: ffff88801bb0c880
RDX: 0000000000000100 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900000074f0 R08: ffffffff8a6b3a6a R09: ffff888012677b40
R10: dffffc0000000000 R11: fffffbfff203a13e R12: ffffc90000007470
R13: 1ffff92000000e8e R14: 0000000000000001 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7b9a67e000 CR3: 000000003ea02000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
pol_lookup_func include/net/ip6_fib.h:616 [inline]
fib6_rule_lookup+0x58c/0x790 net/ipv6/fib6_rules.c:117
ip6_route_input_lookup net/ipv6/route.c:2300 [inline]
ip6_route_input+0x859/0xd90 net/ipv6/route.c:2596
ip6_rcv_finish+0x144/0x180 net/ipv6/ip6_input.c:77
NF_HOOK+0x3a4/0x450 include/linux/netfilter.h:314
__netif_receive_skb_one_core net/core/dev.c:5670 [inline]
__netif_receive_skb+0x1ea/0x650 net/core/dev.c:5783
process_backlog+0x662/0x15b0 net/core/dev.c:6115
__napi_poll+0xcb/0x490 net/core/dev.c:6779
napi_poll net/core/dev.c:6848 [inline]
net_rx_action+0x89b/0x1240 net/core/dev.c:6970
handle_softirqs+0x2c5/0x980 kernel/softirq.c:554
do_softirq+0x11b/0x1e0 kernel/softirq.c:455
</IRQ>
<TASK>
__local_bh_enable_ip+0x1bb/0x200 kernel/softirq.c:382
local_bh_enable include/linux/bottom_half.h:33 [inline]
netif_rx+0x83/0x90 net/core/dev.c:5255
macvlan_broadcast+0x3c4/0x670 drivers/net/macvlan.c:290
macvlan_process_broadcast+0x50e/0x7f0 drivers/net/macvlan.c:338
process_one_work kernel/workqueue.c:3229 [inline]
process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310
worker_thread+0x870/0xd30 kernel/workqueue.c:3391
kthread+0x2f0/0x390 kernel/kthread.c:389
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:rt6_get_pcpu_route net/ipv6/route.c:1408 [inline]
RIP: 0010:ip6_pol_route+0x4d1/0x15d0 net/ipv6/route.c:2264
Code: 93 f7 48 8b 03 65 4c 8b 30 31 ff 4c 89 f6 e8 86 b4 29 f7 4d 85 f6 0f 84 da 00 00 00 49 8d 9e 98 00 00 00 48 89 d8 48 c1 e8 03 <42> 0f b6 04 38 84 c0 0f 85 12 0f 00 00 44 8b 3b 31 ff 44 89 fe e8
RSP: 0018:ffffc900000073a0 EFLAGS: 00010202
RAX: 0000000000000013 RBX: 0000000000000099 RCX: ffff88801bb0c880
RDX: 0000000000000100 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900000074f0 R08: ffffffff8a6b3a6a R09: ffff888012677b40
R10: dffffc0000000000 R11: fffffbfff203a13e R12: ffffc90000007470
R13: 1ffff92000000e8e R14: 0000000000000001 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7b9a67e000 CR3: 000000003ea02000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 93 xchg %eax,%ebx
1: f7 48 8b 03 65 4c 8b testl $0x8b4c6503,-0x75(%rax)
8: 30 31 xor %dh,(%rcx)
a: ff 4c 89 f6 decl -0xa(%rcx,%rcx,4)
e: e8 86 b4 29 f7 call 0xf729b499
13: 4d 85 f6 test %r14,%r14
16: 0f 84 da 00 00 00 je 0xf6
1c: 49 8d 9e 98 00 00 00 lea 0x98(%r14),%rbx
23: 48 89 d8 mov %rbx,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 0f b6 04 38 movzbl (%rax,%r15,1),%eax <-- trapping instruction
2f: 84 c0 test %al,%al
31: 0f 85 12 0f 00 00 jne 0xf49
37: 44 8b 3b mov (%rbx),%r15d
3a: 31 ff xor %edi,%edi
3c: 44 89 fe mov %r15d,%esi
3f: e8 .byte 0xe8


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