[moderation] [net?] [bpf?] general protection fault in xdp_do_generic_redirect

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 642a16ca7994 Add linux-next specific files for 20240627
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=151600be980000
kernel config: https://syzkaller.appspot.com/x/.config?x=ba15715f73169384
dashboard link: https://syzkaller.appspot.com/bug?extid=87f05747fb345549036d
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [and...@kernel.org a...@kernel.org b...@vger.kernel.org dan...@iogearbox.net da...@davemloft.net edd...@gmail.com edum...@google.com hao...@google.com john.fa...@gmail.com jo...@kernel.org kps...@kernel.org ku...@kernel.org linux-...@vger.kernel.org marti...@linux.dev net...@vger.kernel.org pab...@redhat.com s...@fomichev.me so...@kernel.org yongho...@linux.dev]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/72ed10c6e9be/disk-642a16ca.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f2ca81ede1c4/vmlinux-642a16ca.xz
kernel image: https://storage.googleapis.com/syzbot-assets/af14c94fa854/bzImage-642a16ca.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+87f057...@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000007: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f]
CPU: 1 UID: 0 PID: 6705 Comm: syz.2.436 Not tainted 6.10.0-rc5-next-20240627-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
RIP: 0010:bpf_net_ctx_get_ri include/linux/filter.h:788 [inline]
RIP: 0010:xdp_do_generic_redirect+0x7e/0x8f0 net/core/filter.c:4508
Code: 3c 01 00 74 12 48 89 df e8 ef f2 90 f8 48 b8 00 00 00 00 00 fc ff df 48 89 5c 24 48 48 8b 1b 4c 8d 73 38 4d 89 f7 49 c1 ef 03 <41> 0f b6 04 07 84 c0 0f 85 37 06 00 00 41 8b 2e 89 ee 83 e6 02 31
RSP: 0018:ffffc900095a77f8 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 1ffff110045f6a81
RDX: ffffc90011096000 RSI: 0000000000001c41 RDI: 0000000000001c42
RBP: ffffc900095a79b0 R08: 0000000000000005 R09: ffffffff895f485e
R10: 0000000000000003 R11: ffff888022fb3c00 R12: ffffc900095a7b60
R13: 1ffff920012b4f1c R14: 0000000000000038 R15: 0000000000000007
FS: 00007fce5ceb76c0(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020011000 CR3: 0000000021d3a000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
do_xdp_generic+0x884/0xb90 net/core/dev.c:5139
tun_get_user+0x2805/0x4560 drivers/net/tun.c:1924
tun_chr_write_iter+0x113/0x1f0 drivers/net/tun.c:2048
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0xa72/0xc90 fs/read_write.c:590
ksys_write+0x1a0/0x2c0 fs/read_write.c:643
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fce5c1746df
Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 8b 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 8c 02 00 48
RSP: 002b:00007fce5ceb7010 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fce5c303fa0 RCX: 00007fce5c1746df
RDX: 000000000000fdef RSI: 0000000020001540 RDI: 00000000000000c8
RBP: 00007fce5c1f6756 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000fdef R11: 0000000000000293 R12: 0000000000000000
R13: 000000000000000b R14: 00007fce5c303fa0 R15: 00007ffcb6ee1f58
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:bpf_net_ctx_get_ri include/linux/filter.h:788 [inline]
RIP: 0010:xdp_do_generic_redirect+0x7e/0x8f0 net/core/filter.c:4508
Code: 3c 01 00 74 12 48 89 df e8 ef f2 90 f8 48 b8 00 00 00 00 00 fc ff df 48 89 5c 24 48 48 8b 1b 4c 8d 73 38 4d 89 f7 49 c1 ef 03 <41> 0f b6 04 07 84 c0 0f 85 37 06 00 00 41 8b 2e 89 ee 83 e6 02 31
RSP: 0018:ffffc900095a77f8 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 1ffff110045f6a81
RDX: ffffc90011096000 RSI: 0000000000001c41 RDI: 0000000000001c42
RBP: ffffc900095a79b0 R08: 0000000000000005 R09: ffffffff895f485e
R10: 0000000000000003 R11: ffff888022fb3c00 R12: ffffc900095a7b60
R13: 1ffff920012b4f1c R14: 0000000000000038 R15: 0000000000000007
FS: 00007fce5ceb76c0(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020011000 CR3: 0000000021d3a000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 3c 01 cmp $0x1,%al
2: 00 74 12 48 add %dh,0x48(%rdx,%rdx,1)
6: 89 df mov %ebx,%edi
8: e8 ef f2 90 f8 call 0xf890f2fc
d: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
14: fc ff df
17: 48 89 5c 24 48 mov %rbx,0x48(%rsp)
1c: 48 8b 1b mov (%rbx),%rbx
1f: 4c 8d 73 38 lea 0x38(%rbx),%r14
23: 4d 89 f7 mov %r14,%r15
26: 49 c1 ef 03 shr $0x3,%r15
* 2a: 41 0f b6 04 07 movzbl (%r15,%rax,1),%eax <-- trapping instruction
2f: 84 c0 test %al,%al
31: 0f 85 37 06 00 00 jne 0x66e
37: 41 8b 2e mov (%r14),%ebp
3a: 89 ee mov %ebp,%esi
3c: 83 e6 02 and $0x2,%esi
3f: 31 .byte 0x31


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