From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from www62.your-server.de (www62.your-server.de [213.133.104.62]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D92DE3033E9; Wed, 4 Mar 2026 08:20:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.133.104.62 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772612453; cv=none; b=c0EmTv5qNznjlUGg6nURLDdXG4jSae7LkVV43fkvixg/g8IECJW/Ej+ObACy6jl+BUzYWo8Hjh4yUI98ERThpTZNWfbsbxknKOYLXLnS8t6jX+9QaROVGVFR7UuivjgbWq08aU13zwaDjrD88JuXDWyMebwc8WTCZzQ+UNddjMo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772612453; c=relaxed/simple; bh=Yzvz2OcX/hibfB+ZWQ8QvVfOQna2FRgXWAoVtODTmZk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Lt78PkFs+SN45f6Pv5UCM1oVG2dbFPafWqjNd62qx2AK80fHdwe9cQBGFPV9rJAv+ukEaLiAWLo+J852m/EZUkFq4gvsUN/jgdkbNnPeX2D7Qmp9DYH2aDZd2hyoDDX/tFXyIpLk8y+yavgKQAR+uOBrbr2xQsDvLZiTwIIQPG8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=iogearbox.net; spf=pass smtp.mailfrom=iogearbox.net; dkim=pass (2048-bit key) header.d=iogearbox.net header.i=@iogearbox.net header.b=ZPsG5A2W; arc=none smtp.client-ip=213.133.104.62 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=iogearbox.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=iogearbox.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=iogearbox.net header.i=@iogearbox.net header.b="ZPsG5A2W" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=iogearbox.net; s=default2302; h=Content-Transfer-Encoding:Content-Type: In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date:Message-ID:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID; bh=e2vLRe8Ez7+7nnLlb+6zDAS5O4Vu0VVVu6ABOx3M68A=; b=ZPsG5A2Wm9WD2hSniEVzfQpt1o FRttmdURymDPemiWMH538njtm2DKCAETKlQ/FwfoERY7jMY3Boj9p5DbnKwjI0X/wpZqudGeJJkXw e1/fRQ1lpbRAT9iI71A5QIvZSHJmEl9Ailon9/IoUKofV9rp7VtQsxxyARdKUpaM6XjwusBbH8J82 Pi9JMxfhm3PofRjyN1ZCByYESUNG37aMuS2QcAIxIgNz/VusQhK+Hp1Hmydk7DsZWjdBvdkMI5qR3 KaGtiAi3s9WN/0DDs7xbaMjpPcouo1y237Xp/lbrmAU7HEKwvXNYykBqr9blItLT2GQzK+Zibfb9R G8XrNiZw==; Received: from sslproxy03.your-server.de ([88.198.220.132]) by www62.your-server.de with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.96.2) (envelope-from ) id 1vxhTG-000NSi-2n; Wed, 04 Mar 2026 09:20:42 +0100 Received: from localhost ([127.0.0.1]) by sslproxy03.your-server.de with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1vxhTE-000NtK-2f; Wed, 04 Mar 2026 09:20:41 +0100 Message-ID: <4d15be93-b497-4499-996d-9f3a67a2abc6@iogearbox.net> Date: Wed, 4 Mar 2026 09:20:27 +0100 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net v4 1/2] bonding: fix null-ptr-deref in bond_rr_gen_slave_id() To: Jiayuan Chen , jv@jvosburgh.net, netdev@vger.kernel.org Cc: jiayuan.chen@shopee.com, syzbot+80e046b8da2820b6ba73@syzkaller.appspotmail.com, Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Alexei Starovoitov , Jesper Dangaard Brouer , John Fastabend , Stanislav Fomichev , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , KP Singh , Hao Luo , Jiri Olsa , Shuah Khan , Sebastian Andrzej Siewior , Clark Williams , Steven Rostedt , Jussi Maki , linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-rt-devel@lists.linux.dev References: <20260304074301.35482-1-jiayuan.chen@linux.dev> <20260304074301.35482-2-jiayuan.chen@linux.dev> Content-Language: en-US From: Daniel Borkmann Autocrypt: addr=daniel@iogearbox.net; keydata= xsFNBGNAkI0BEADiPFmKwpD3+vG5nsOznvJgrxUPJhFE46hARXWYbCxLxpbf2nehmtgnYpAN 2HY+OJmdspBntWzGX8lnXF6eFUYLOoQpugoJHbehn9c0Dcictj8tc28MGMzxh4aK02H99KA8 VaRBIDhmR7NJxLWAg9PgneTFzl2lRnycv8vSzj35L+W6XT7wDKoV4KtMr3Szu3g68OBbp1TV HbJH8qe2rl2QKOkysTFRXgpu/haWGs1BPpzKH/ua59+lVQt3ZupePpmzBEkevJK3iwR95TYF 06Ltpw9ArW/g3KF0kFUQkGXYXe/icyzHrH1Yxqar/hsJhYImqoGRSKs1VLA5WkRI6KebfpJ+ RK7Jxrt02AxZkivjAdIifFvarPPu0ydxxDAmgCq5mYJ5I/+BY0DdCAaZezKQvKw+RUEvXmbL 94IfAwTFA1RAAuZw3Rz5SNVz7p4FzD54G4pWr3mUv7l6dV7W5DnnuohG1x6qCp+/3O619R26 1a7Zh2HlrcNZfUmUUcpaRPP7sPkBBLhJfqjUzc2oHRNpK/1mQ/+mD9CjVFNz9OAGD0xFzNUo yOFu/N8EQfYD9lwntxM0dl+QPjYsH81H6zw6ofq+jVKcEMI/JAgFMU0EnxrtQKH7WXxhO4hx 3DFM7Ui90hbExlFrXELyl/ahlll8gfrXY2cevtQsoJDvQLbv7QARAQABzSZEYW5pZWwgQm9y a21hbm4gPGRhbmllbEBpb2dlYXJib3gubmV0PsLBkQQTAQoAOxYhBCrUdtCTcZyapV2h+93z cY/jfzlXBQJjQJCNAhsDBQkHhM4ACAsJCAcNDAsKBRUKCQgLAh4BAheAAAoJEN3zcY/jfzlX dkUQAIFayRgjML1jnwKs7kvfbRxf11VI57EAG8a0IvxDlNKDcz74mH66HMyhMhPqCPBqphB5 ZUjN4N5I7iMYB/oWUeohbuudH4+v6ebzzmgx/EO+jWksP3gBPmBeeaPv7xOvN/pPDSe/0Ywp dHpl3Np2dS6uVOMnyIsvmUGyclqWpJgPoVaXrVGgyuer5RpE/a3HJWlCBvFUnk19pwDMMZ8t 0fk9O47HmGh9Ts3O8pGibfdREcPYeGGqRKRbaXvcRO1g5n5x8cmTm0sQYr2xhB01RJqWrgcj ve1TxcBG/eVMmBJefgCCkSs1suriihfjjLmJDCp9XI/FpXGiVoDS54TTQiKQinqtzP0jv+TH 1Ku+6x7EjLoLH24ISGyHRmtXJrR/1Ou22t0qhCbtcT1gKmDbTj5TcqbnNMGWhRRTxgOCYvG0 0P2U6+wNj3HFZ7DePRNQ08bM38t8MUpQw4Z2SkM+jdqrPC4f/5S8JzodCu4x80YHfcYSt+Jj ipu1Ve5/ftGlrSECvy80ZTKinwxj6lC3tei1bkI8RgWZClRnr06pirlvimJ4R0IghnvifGQb M1HwVbht8oyUEkOtUR0i0DMjk3M2NoZ0A3tTWAlAH8Y3y2H8yzRrKOsIuiyKye9pWZQbCDu4 ZDKELR2+8LUh+ja1RVLMvtFxfh07w9Ha46LmRhpCzsFNBGNAkI0BEADJh65bNBGNPLM7cFVS nYG8tqT+hIxtR4Z8HQEGseAbqNDjCpKA8wsxQIp0dpaLyvrx4TAb/vWIlLCxNu8Wv4W1JOST wI+PIUCbO/UFxRy3hTNlb3zzmeKpd0detH49bP/Ag6F7iHTwQQRwEOECKKaOH52tiJeNvvyJ pPKSKRhmUuFKMhyRVK57ryUDgowlG/SPgxK9/Jto1SHS1VfQYKhzMn4pWFu0ILEQ5x8a0RoX k9p9XkwmXRYcENhC1P3nW4q1xHHlCkiqvrjmWSbSVFYRHHkbeUbh6GYuCuhqLe6SEJtqJW2l EVhf5AOp7eguba23h82M8PC4cYFl5moLAaNcPHsdBaQZznZ6NndTtmUENPiQc2EHjHrrZI5l kRx9hvDcV3Xnk7ie0eAZDmDEbMLvI13AvjqoabONZxra5YcPqxV2Biv0OYp+OiqavBwmk48Z P63kTxLddd7qSWbAArBoOd0wxZGZ6mV8Ci/ob8tV4rLSR/UOUi+9QnkxnJor14OfYkJKxot5 hWdJ3MYXjmcHjImBWplOyRiB81JbVf567MQlanforHd1r0ITzMHYONmRghrQvzlaMQrs0V0H 5/sIufaiDh7rLeZSimeVyoFvwvQPx5sXhjViaHa+zHZExP9jhS/WWfFE881fNK9qqV8pi+li 2uov8g5yD6hh+EPH6wARAQABwsF8BBgBCgAmFiEEKtR20JNxnJqlXaH73fNxj+N/OVcFAmNA kI0CGwwFCQeEzgAACgkQ3fNxj+N/OVfFMhAA2zXBUzMLWgTm6iHKAPfz3xEmjtwCF2Qv/TT3 KqNUfU3/0VN2HjMABNZR+q3apm+jq76y0iWroTun8Lxo7g89/VDPLSCT0Nb7+VSuVR/nXfk8 R+OoXQgXFRimYMqtP+LmyYM5V0VsuSsJTSnLbJTyCJVu8lvk3T9B0BywVmSFddumv3/pLZGn 17EoKEWg4lraXjPXnV/zaaLdV5c3Olmnj8vh+14HnU5Cnw/dLS8/e8DHozkhcEftOf+puCIl Awo8txxtLq3H7KtA0c9kbSDpS+z/oT2S+WtRfucI+WN9XhvKmHkDV6+zNSH1FrZbP9FbLtoE T8qBdyk//d0GrGnOrPA3Yyka8epd/bXA0js9EuNknyNsHwaFrW4jpGAaIl62iYgb0jCtmoK/ rCsv2dqS6Hi8w0s23IGjz51cdhdHzkFwuc8/WxI1ewacNNtfGnorXMh6N0g7E/r21pPeMDFs rUD9YI1Je/WifL/HbIubHCCdK8/N7rblgUrZJMG3W+7vAvZsOh/6VTZeP4wCe7Gs/cJhE2gI DmGcR+7rQvbFQC4zQxEjo8fNaTwjpzLM9NIp4vG9SDIqAm20MXzLBAeVkofixCsosUWUODxP owLbpg7pFRJGL9YyEHpS7MGPb3jSLzucMAFXgoI8rVqoq6si2sxr2l0VsNH5o3NgoAgJNIg= In-Reply-To: <20260304074301.35482-2-jiayuan.chen@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: Clear (ClamAV 1.4.3/27929/Tue Mar 3 08:24:19 2026) On 3/4/26 8:42 AM, Jiayuan Chen wrote: > From: Jiayuan Chen > > bond_rr_gen_slave_id() dereferences bond->rr_tx_counter without a NULL > check. rr_tx_counter is a per-CPU counter only allocated in bond_open() > when the bond mode is round-robin. If the bond device was never brought > up, rr_tx_counter remains NULL, causing a null-ptr-deref. > > The XDP redirect path can reach this code even when the bond is not up: > bpf_master_redirect_enabled_key is a global static key, so when any bond > device has native XDP attached, the XDP_TX -> xdp_master_redirect() > interception is enabled for all bond slaves system-wide. This allows the > path xdp_master_redirect() -> bond_xdp_get_xmit_slave() -> > bond_xdp_xmit_roundrobin_slave_get() -> bond_rr_gen_slave_id() to be > reached on a bond that was never opened. > > Fix this by allocating rr_tx_counter unconditionally in bond_init() > (ndo_init), which is called by register_netdevice() and covers both > device creation paths (bond_create() and bond_newlink()). This also > handles the case where bond mode is changed to round-robin after device > creation. The conditional allocation in bond_open() is removed. Since > bond_destructor() already unconditionally calls > free_percpu(bond->rr_tx_counter), the lifecycle is clean: allocate at > ndo_init, free at destructor. > > Note: rr_tx_counter is only used by round-robin mode, so this > deliberately allocates a per-cpu u32 that goes unused for other modes. > Conditional allocation (e.g., in bond_option_mode_set) was considered > but rejected: the XDP path can race with mode changes on a downed bond, > and adding memory barriers to the XDP hot path is not justified for > saving 4 bytes per CPU. Arguably it's a corner case, but could we not just do sth like this to actually check if the device is up and if not drop? diff --git a/net/core/filter.c b/net/core/filter.c index ba019ded773d..c447fd989a27 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -4387,6 +4387,9 @@ u32 xdp_master_redirect(struct xdp_buff *xdp) struct net_device *master, *slave; master = netdev_master_upper_dev_get_rcu(xdp->rxq->dev); + if (unlikely(!(master->flags & IFF_UP))) + return XDP_ABORTED; + slave = master->netdev_ops->ndo_xdp_get_xmit_slave(master, xdp); if (slave && slave != xdp->rxq->dev) { /* The target device is different from the receiving device, so