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Date: Thu, 8 Jul 2021 12:26:59 +0200
From: Jesper Dangaard Brouer <jbrouer@...hat.com>
To: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, bpf@...r.kernel.org
Cc: brouer@...hat.com, "David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>,
Martin KaFai Lau <kafai@...com>,
Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
John Fastabend <john.fastabend@...il.com>,
KP Singh <kpsingh@...nel.org>,
Jesper Dangaard Brouer <hawk@...nel.org>,
netdev@...r.kernel.org, Abaci <abaci@...ux.alibaba.com>,
Dust Li <dust.li@...ux.alibaba.com>,
David Ahern <dsahern@...nel.org>
Subject: Re: [PATCH bpf] bpf: fix for BUG: kernel NULL pointer dereference,
address: 0000000000000000
Thanks for catching this.
Cc: Ahern, are you okay with disabling this for the
bpf_prog_test_run_xdp() infra?
I don't think the selftests/bpf (e.g. prog_tests/xdp_devmap_attach.c)
use the bpf_prog_test_run, right?
Acked-by: Jesper Dangaard Brouer <brouer@...hat.com>
On 08/07/2021 10.04, Xuan Zhuo wrote:
> These two types of xdp prog(BPF_XDP_DEVMAP, BPF_XDP_CPUMAP) will not be
> executed directly in the driver, we should not directly run these two
> XDP progs here. To run these two situations, there must be some special
> preparations, otherwise it may cause kernel exceptions.
>
> For more reference dev_xdp_attach().
>
> [ 46.982479] BUG: kernel NULL pointer dereference, address: 0000000000000000
> [ 46.984295] #PF: supervisor read access in kernel mode
> [ 46.985777] #PF: error_code(0x0000) - not-present page
> [ 46.987227] PGD 800000010dca4067 P4D 800000010dca4067 PUD 10dca6067 PMD 0
> [ 46.989201] Oops: 0000 [#1] SMP PTI
> [ 46.990304] CPU: 7 PID: 562 Comm: a.out Not tainted 5.13.0+ #44
> [ 46.992001] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/24
> [ 46.995113] RIP: 0010:___bpf_prog_run+0x17b/0x1710
> [ 46.996586] Code: 49 03 14 cc e8 76 f6 fe ff e9 ad fe ff ff 0f b6 43 01 48 0f bf 4b 02 48 83 c3 08 89 c2 83 e0 0f c0 ea 04 02
> [ 47.001562] RSP: 0018:ffffc900005afc58 EFLAGS: 00010246
> [ 47.003115] RAX: 0000000000000000 RBX: ffffc9000023f068 RCX: 0000000000000000
> [ 47.005163] RDX: 0000000000000000 RSI: 0000000000000079 RDI: ffffc900005afc98
> [ 47.007135] RBP: 0000000000000000 R08: ffffc9000023f048 R09: c0000000ffffdfff
> [ 47.009171] R10: 0000000000000001 R11: ffffc900005afb40 R12: ffffc900005afc98
> [ 47.011172] R13: 0000000000000001 R14: 0000000000000001 R15: ffffffff825258a8
> [ 47.013244] FS: 00007f04a5207580(0000) GS:ffff88842fdc0000(0000) knlGS:0000000000000000
> [ 47.015705] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 47.017475] CR2: 0000000000000000 CR3: 0000000100182005 CR4: 0000000000770ee0
> [ 47.019558] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 47.021595] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [ 47.023574] PKRU: 55555554
> [ 47.024571] Call Trace:
> [ 47.025424] __bpf_prog_run32+0x32/0x50
> [ 47.026296] ? printk+0x53/0x6a
> [ 47.027066] ? ktime_get+0x39/0x90
> [ 47.027895] bpf_test_run.cold.28+0x23/0x123
> [ 47.028866] ? printk+0x53/0x6a
> [ 47.029630] bpf_prog_test_run_xdp+0x149/0x1d0
> [ 47.030649] __sys_bpf+0x1305/0x23d0
> [ 47.031482] __x64_sys_bpf+0x17/0x20
> [ 47.032316] do_syscall_64+0x3a/0x80
> [ 47.033165] entry_SYSCALL_64_after_hwframe+0x44/0xae
> [ 47.034254] RIP: 0033:0x7f04a51364dd
> [ 47.035133] Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 48
> [ 47.038768] RSP: 002b:00007fff8f9fc518 EFLAGS: 00000213 ORIG_RAX: 0000000000000141
> [ 47.040344] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f04a51364dd
> [ 47.041749] RDX: 0000000000000048 RSI: 0000000020002a80 RDI: 000000000000000a
> [ 47.043171] RBP: 00007fff8f9fc530 R08: 0000000002049300 R09: 0000000020000100
> [ 47.044626] R10: 0000000000000004 R11: 0000000000000213 R12: 0000000000401070
> [ 47.046088] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> [ 47.047579] Modules linked in:
> [ 47.048318] CR2: 0000000000000000
> [ 47.049120] ---[ end trace 7ad34443d5be719a ]---
> [ 47.050273] RIP: 0010:___bpf_prog_run+0x17b/0x1710
> [ 47.051343] Code: 49 03 14 cc e8 76 f6 fe ff e9 ad fe ff ff 0f b6 43 01 48 0f bf 4b 02 48 83 c3 08 89 c2 83 e0 0f c0 ea 04 02
> [ 47.054943] RSP: 0018:ffffc900005afc58 EFLAGS: 00010246
> [ 47.056068] RAX: 0000000000000000 RBX: ffffc9000023f068 RCX: 0000000000000000
> [ 47.057522] RDX: 0000000000000000 RSI: 0000000000000079 RDI: ffffc900005afc98
> [ 47.058961] RBP: 0000000000000000 R08: ffffc9000023f048 R09: c0000000ffffdfff
> [ 47.060390] R10: 0000000000000001 R11: ffffc900005afb40 R12: ffffc900005afc98
> [ 47.061803] R13: 0000000000000001 R14: 0000000000000001 R15: ffffffff825258a8
> [ 47.063249] FS: 00007f04a5207580(0000) GS:ffff88842fdc0000(0000) knlGS:0000000000000000
> [ 47.065070] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 47.066307] CR2: 0000000000000000 CR3: 0000000100182005 CR4: 0000000000770ee0
> [ 47.067747] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 47.069217] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [ 47.070652] PKRU: 55555554
> [ 47.071318] Kernel panic - not syncing: Fatal exception
> [ 47.072854] Kernel Offset: disabled
> [ 47.073683] ---[ end Kernel panic - not syncing: Fatal exception ]---
>
> Reported-by: Abaci <abaci@...ux.alibaba.com>
> Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
> Reviewed-by: Dust Li <dust.li@...ux.alibaba.com>
> ---
> net/bpf/test_run.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
> index aa47af349ba8..17227e0b277b 100644
> --- a/net/bpf/test_run.c
> +++ b/net/bpf/test_run.c
> @@ -701,6 +701,12 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
> void *data;
> int ret;
>
> + if (prog->expected_attach_type == BPF_XDP_DEVMAP)
> + return -EINVAL;
> +
> + if (prog->expected_attach_type == BPF_XDP_CPUMAP)
> + return -EINVAL;
> +
> if (kattr->test.ctx_in || kattr->test.ctx_out)
> return -EINVAL;
>
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