Re: KMSAN: uninit-value in ip_tunnel_xmit

[Eric Dumazet]

On Thu, Dec 7, 2023 at 2:27 PM xingwei lee <xrivendell7@xxxxxxxxx> wrote:
>
> Hello,
>
> When fuzzing the latest upstream linux 6.7-rc4,  the following crash
> was triggered.
> HEAD commit: bee0e7762ad2c6025b9f5245c040fcc36ef2bde8
>
> If you fix this issue, please add the following tag to the commit:
> Reported-by: xingwei Lee <xrivendell7@xxxxxxxxx>
>
> console_log: https://gist.github.com/xrivendell7/b41fbc928cd203823783fd90c98b6583#file-console_log
> report: https://gist.github.com/xrivendell7/b41fbc928cd203823783fd90c98b6583#file-report
> kernel commit: bee0e7762ad2c6025b9f5245c040fcc36ef2bde8
> kernel config: https://syzkaller.appspot.com/text?tag=KernelConfig&x=ce27066613dacbb6
> repro.c: https://gist.github.com/xrivendell7/b41fbc928cd203823783fd90c98b6583#file-repro-c
> repro.txt: https://gist.github.com/xrivendell7/b41fbc928cd203823783fd90c98b6583#file-repro-txt
>
> In the lasted kernel: bee0e7762ad2c6025b9f5245c040fcc36ef2bde8 the
> [  199.471467][ T8590] =====================================================
> [  199.475015][ T8590] BUG: KMSAN: uninit-value in ip_tunnel_xmit+0x857/0x3e80
> [  199.478180][ T8590]  ip_tunnel_xmit+0x857/0x3e80
> [  199.480541][ T8590]  ipgre_xmit+0xd1c/0xe20
> [  199.482393][ T8590]  dev_hard_start_xmit+0x247/0xa10
> [  199.484530][ T8590]  __dev_queue_xmit+0x33b8/0x5130
> [  199.486433][ T8590]  __bpf_redirect+0xdd7/0x1600
> [  199.488258][ T8590]  bpf_clone_redirect+0x328/0x470
> [  199.490250][ T8590]  ___bpf_prog_run+0x2180/0xdb80
> [  199.491997][ T8590]  __bpf_prog_run512+0xb5/0xe0
> [  199.493691][ T8590]  bpf_test_run+0x482/0xb00
> [  199.495215][ T8590]  bpf_prog_test_run_skb+0x14e5/0x1f20
> [  199.497026][ T8590]  bpf_prog_test_run+0x6af/0xac0
> [  199.498701][ T8590]  __sys_bpf+0x649/0xd60
> [  199.500029][ T8590]  __x64_sys_bpf+0xa0/0xe0
> [  199.501411][ T8590]  do_syscall_64+0x44/0x110
> [  199.502757][ T8590]  entry_SYSCALL_64_after_hwframe+0x63/0x6b
> [  199.504463][ T8590]
> [  199.505159][ T8590] Uninit was created at:
> [  199.506344][ T8590]  slab_post_alloc_hook+0x129/0xa70
> [  199.507690][ T8590]  kmem_cache_alloc_node+0x5e9/0xb10
> [  199.509191][ T8590]  kmalloc_reserve+0x13d/0x4a0
> [  199.510411][ T8590]  pskb_expand_head+0x226/0x1a00
> [  199.511657][ T8590]  skb_ensure_writable+0x3d3/0x460
> [  199.512905][ T8590]  bpf_clone_redirect+0x17f/0x470
> [  199.514135][ T8590]  ___bpf_prog_run+0x2180/0xdb80
> [  199.515325][ T8590]  __bpf_prog_run512+0xb5/0xe0
> [  199.516479][ T8590]  bpf_test_run+0x482/0xb00
> [  199.517580][ T8590]  bpf_prog_test_run_skb+0x14e5/0x1f20
> [  199.518901][ T8590]  bpf_prog_test_run+0x6af/0xac0
> [  199.520015][ T8590]  __sys_bpf+0x649/0xd60
> [  199.520996][ T8590]  __x64_sys_bpf+0xa0/0xe0
> [  199.521949][ T8590]  do_syscall_64+0x44/0x110
> [  199.522926][ T8590]  entry_SYSCALL_64_after_hwframe+0x63/0x6b
>
> and I notice the problem is reported at 2018/2020 and seems fixed twice.
>
> https://syzkaller.appspot.com/bug?id=f62d236e2fceaeb104f4e8f77d2324ef9da4b41b
> https://syzkaller.appspot.com/bug?extid=4a2c52677a8a1aa283cb
>
>
>
> If you fix this issue, please add the following tag to the commit:
> Reported-by: Yikebaer Aizezi <yikebaer61@xxxxxxxxx>

I think a fix was merged into the net tree yesterday, please double check.

80d875cfc9d3711a029f234ef7d680db79e8fa4b ipv4: ip_gre: Avoid
skb_pull() failure in ipgre_xmit()