[syzbot] [netfilter?] general protection fault in nft_fib6_eval (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 01792bc3e5bd net: ti: icssg-prueth: Fix HSR and switch off..
git tree: net
console output: https://syzkaller.appspot.com/x/log.txt?x=108ec3bc580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c321f33e4545e2a1
dashboard link: https://syzkaller.appspot.com/bug?extid=109521837481c8e96ea5
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/deae9487bd6c/disk-01792bc3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1bb0140fd491/vmlinux-01792bc3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/bd9ec803c379/bzImage-01792bc3.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+109521...@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 UID: 0 PID: 8151 Comm: syz.2.634 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:nft_fib6_eval+0x7cd/0xc20 net/ipv6/netfilter/nft_fib_ipv6.c:-1
Code: 4c 89 f3 48 81 c3 d8 00 00 00 48 89 d8 48 c1 e8 03 42 80 3c 20 00 74 08 48 89 df e8 8d df dd f7 48 8b 1b 48 89 d8 48 c1 e8 03 <42> 80 3c 20 00 74 08 48 89 df e8 74 df dd f7 48 8b 3b 48 8b 5c 24
RSP: 0018:ffffc9001c59f000 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000002
RDX: ffff88802fcabc00 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9001c59f1d0 R08: ffffffff8fa37e37 R09: 1ffffffff1f46fc6
R10: dffffc0000000000 R11: fffffbfff1f46fc7 R12: dffffc0000000000
R13: ffffc9001c59f0f0 R14: ffff88807f6db500 R15: ffff88807f6db560
FS: 00007faeb51596c0(0000) GS:ffff888125c1b000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7baea82f98 CR3: 000000007e12a000 CR4: 00000000003526f0
Call Trace:
<TASK>
expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline]
nft_do_chain+0x409/0x1920 net/netfilter/nf_tables_core.c:285
nft_do_chain_inet+0x25d/0x340 net/netfilter/nft_chain_filter.c:161
nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
nf_hook_slow+0xc2/0x220 net/netfilter/core.c:623
nf_hook include/linux/netfilter.h:273 [inline]
NF_HOOK+0x206/0x3a0 include/linux/netfilter.h:316
__netif_receive_skb_one_core net/core/dev.c:5991 [inline]
__netif_receive_skb+0xd3/0x380 net/core/dev.c:6104
netif_receive_skb_internal net/core/dev.c:6190 [inline]
netif_receive_skb+0x1cb/0x790 net/core/dev.c:6249
tun_rx_batched+0x1b9/0x730 drivers/net/tun.c:1485
tun_get_user+0x2aa2/0x3e20 drivers/net/tun.c:1950
tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:1996
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0x5c9/0xb30 fs/read_write.c:686
ksys_write+0x145/0x250 fs/read_write.c:738
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7faeb438d69f
Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 92 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 4c 93 02 00 48
RSP: 002b:00007faeb5159000 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007faeb45b5fa0 RCX: 00007faeb438d69f
RDX: 0000000000000046 RSI: 0000200000000b00 RDI: 00000000000000c8
RBP: 00007faeb4411e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000046 R11: 0000000000000293 R12: 0000000000000000
R13: 00007faeb45b6038 R14: 00007faeb45b5fa0 R15: 00007ffcdc4d36a8
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:nft_fib6_eval+0x7cd/0xc20 net/ipv6/netfilter/nft_fib_ipv6.c:-1
Code: 4c 89 f3 48 81 c3 d8 00 00 00 48 89 d8 48 c1 e8 03 42 80 3c 20 00 74 08 48 89 df e8 8d df dd f7 48 8b 1b 48 89 d8 48 c1 e8 03 <42> 80 3c 20 00 74 08 48 89 df e8 74 df dd f7 48 8b 3b 48 8b 5c 24
RSP: 0018:ffffc9001c59f000 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000002
RDX: ffff88802fcabc00 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9001c59f1d0 R08: ffffffff8fa37e37 R09: 1ffffffff1f46fc6
R10: dffffc0000000000 R11: fffffbfff1f46fc7 R12: dffffc0000000000
R13: ffffc9001c59f0f0 R14: ffff88807f6db500 R15: ffff88807f6db560
FS: 00007faeb51596c0(0000) GS:ffff888125c1b000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7baea82f98 CR3: 000000007e12a000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
0: 4c 89 f3 mov %r14,%rbx
3: 48 81 c3 d8 00 00 00 add $0xd8,%rbx
a: 48 89 d8 mov %rbx,%rax
d: 48 c1 e8 03 shr $0x3,%rax
11: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1)
16: 74 08 je 0x20
18: 48 89 df mov %rbx,%rdi
1b: e8 8d df dd f7 call 0xf7dddfad
20: 48 8b 1b mov (%rbx),%rbx
23: 48 89 d8 mov %rbx,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1) <-- trapping instruction
2f: 74 08 je 0x39
31: 48 89 df mov %rbx,%rdi
34: e8 74 df dd f7 call 0xf7dddfad
39: 48 8b 3b mov (%rbx),%rdi
3c: 48 rex.W
3d: 8b .byte 0x8b
3e: 5c pop %rsp
3f: 24 .byte 0x24


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