From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1581E3A381D for ; Wed, 20 May 2026 17:30:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779298206; cv=none; b=TNubhGcyZERLXaXM7jg0LPmTZ0A/XMDdlYYXrMI+IPFyBbEDSDV6ZZn/7wagxxq67oW6V0r3Wx1iriBgmZTRBvgnP4qG3tTwZwo1PQfz06uu3llf+eV15qb3zdhFx+gGbZSUZEb4iutrRyGQd0BxD8sO5qVF2Bulv2LPH3Y3g4c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779298206; c=relaxed/simple; bh=m1qbv6mF9RhZ6Or0RiOGiZvRAZrGbFxjgat4eiSIBh8=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=PUKOi0szVgtnbMH8MF7HpFE1QifFlrYvoORrQ3RIY5F4ZqqfPIuGZI6gtaK28GHHAoq7/3KkCC0cHh2taPI0Y3gevVczWh/+cTxzuAwPijk9nAuSkOg5X0nz2t0tBtgHhSmIpvWTipqSqZC1aCIg8wXVYzIKYQr+qdBoqrLNOeE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--kpberry.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=FwLIl8eA; arc=none smtp.client-ip=209.85.216.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--kpberry.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="FwLIl8eA" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-3692f395339so5070874a91.1 for ; Wed, 20 May 2026 10:30:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1779298204; x=1779903004; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=3V7RUnZHB/rTyjhH2xTvr24MsEKS6M+dSewO19ouvl8=; b=FwLIl8eACwuMvZ5FmwRfrQuxohzBt77wtB7avSrVyxMXp/D85MJEgpa5wMexT39FZo k7V4juKha9UAceB0kh+cGG8wmNv2BfdgA5wYMb1dTMa+rCu0bivBPf4TSC2GaFl93pjj B+0afvc72K9IzspEsYVSqiNLtU0DOWc8n1/0qXiLDM2x0Ac62lV6VWqw+euN1YznEnmm w8LLCa0vrvOEydKYY8e2UjVZElg44SpxbH5Em6N2vKvfd2IQQbmpwMfhemj+qGGZ3I+7 6aKa6eOzVI0Hmk+DYXe6vBCsMAac3X6679u/nscNL56mJAaMIKD3HbMdl+TkrriWYoN5 c7Fg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779298204; x=1779903004; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=3V7RUnZHB/rTyjhH2xTvr24MsEKS6M+dSewO19ouvl8=; b=k5AEUtuuRiAPmB1WDxJAkK22Bh5+WIv8gVsGaXqTkjWi+0BN9HSxU2wlOt0YcSu6pB /t434exGmMECEzrVO5d1uWM06+gYgDxQC0l5QLWIz6HABg5qRsFzDO6AWEHOUkHWciZr Uflz4gCWnzpQobSxBZgQQ2eep15/zBTCIrbG44Ne+VT3xkT3nIgqcBiQKk3LaY/0kTEE 5E0Q7Gy83769InBGbzXEdLG+PjHUZCfabe9fe1wGBcFFrWdjtqIVtof2A0tAlXKpREhJ pi9z2fNZEGtxCim/YqGZxiA9opuEcRppicUuBGVrdA74DbuU9FBXTceCWdrRNE8gc2ot wFxA== X-Forwarded-Encrypted: i=1; AFNElJ8Vh+pDX4FEQATqRoPoeq/NphRiqqoHKN6aJpdhfSXEjXkIzKZVoNk1ew1LZyMSrP8Yl7Uixdg=@vger.kernel.org X-Gm-Message-State: AOJu0YxW6ZfMKnJXVZep8eCosAlnMTsy33h1ZdMzPfiW7EHBPsEHhhVP CD4oKrsvhYmi5sPLpxy1PcmDqZBwk+pNj8Em3wOPJbL/mlu4DE6V/wS4Az28MXjMjK7UigmJ0fG etbthdv6zJQ== X-Received: from pge13.prod.google.com ([2002:a05:6a02:2d0d:b0:c76:6cef:34e7]) (user=kpberry job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a20:7284:b0:39b:fbb2:5e46 with SMTP id adf61e73a8af0-3b22ec589fbmr28304688637.40.1779298204118; Wed, 20 May 2026 10:30:04 -0700 (PDT) Date: Wed, 20 May 2026 17:29:51 +0000 In-Reply-To: <2026052009-vexingly-chokehold-f8f7@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <2026052009-vexingly-chokehold-f8f7@gregkh> X-Mailer: git-send-email 2.54.0.669.g59709faab0-goog Message-ID: <20260520172951.3087955-1-kpberry@google.com> Subject: [PATCH] net: bonding: fix use-after-free in bond_xmit_broadcast() From: Kevin Berry To: gregkh@linuxfoundation.org Cc: bestswngs@gmail.com, chenglongtang@google.com, joneslee@google.com, kpberry@google.com, pabeni@redhat.com, rnj@google.com, sashal@kernel.org, stable@vger.kernel.org, xmei5@asu.edu Content-Type: text/plain; charset="UTF-8" From: Xiang Mei commit 2884bf72fb8f03409e423397319205de48adca16 upstream. bond_xmit_broadcast() reuses the original skb for the last slave (determined by bond_is_last_slave()) and clones it for others. Concurrent slave enslave/release can mutate the slave list during RCU-protected iteration, changing which slave is "last" mid-loop. This causes the original skb to be double-consumed (double-freed). Replace the racy bond_is_last_slave() check with a simple index comparison (i + 1 == slaves_count) against the pre-snapshot slave count taken via READ_ONCE() before the loop. This preserves the zero-copy optimization for the last slave while making the "last" determination stable against concurrent list mutations. The UAF can trigger the following crash: ================================================================== BUG: KASAN: slab-use-after-free in skb_clone Read of size 8 at addr ffff888100ef8d40 by task exploit/147 CPU: 1 UID: 0 PID: 147 Comm: exploit Not tainted 7.0.0-rc3+ #4 PREEMPTLAZY Call Trace: dump_stack_lvl (lib/dump_stack.c:123) print_report (mm/kasan/report.c:379 mm/kasan/report.c:482) kasan_report (mm/kasan/report.c:597) skb_clone (include/linux/skbuff.h:1724 include/linux/skbuff.h:1792 include/linux/skbuff.h:3396 net/core/skbuff.c:2108) bond_xmit_broadcast (drivers/net/bonding/bond_main.c:5334) bond_start_xmit (drivers/net/bonding/bond_main.c:5567 drivers/net/bonding/bond_main.c:5593) dev_hard_start_xmit (include/linux/netdevice.h:5325 include/linux/netdevice.h:5334 net/core/dev.c:3871 net/core/dev.c:3887) __dev_queue_xmit (include/linux/netdevice.h:3601 net/core/dev.c:4838) ip6_finish_output2 (include/net/neighbour.h:540 include/net/neighbour.h:554 net/ipv6/ip6_output.c:136) ip6_finish_output (net/ipv6/ip6_output.c:208 net/ipv6/ip6_output.c:219) ip6_output (net/ipv6/ip6_output.c:250) ip6_send_skb (net/ipv6/ip6_output.c:1985) udp_v6_send_skb (net/ipv6/udp.c:1442) udpv6_sendmsg (net/ipv6/udp.c:1733) __sys_sendto (net/socket.c:730 net/socket.c:742 net/socket.c:2206) __x64_sys_sendto (net/socket.c:2209) do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) Allocated by task 147: Freed by task 147: The buggy address belongs to the object at ffff888100ef8c80 which belongs to the cache skbuff_head_cache of size 224 The buggy address is located 192 bytes inside of freed 224-byte region [ffff888100ef8c80, ffff888100ef8d60) Memory state around the buggy address: ffff888100ef8c00: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc ffff888100ef8c80: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888100ef8d00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff888100ef8d80: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb ffff888100ef8e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== Fixes: 4e5bd03ae346 ("net: bonding: fix bond_xmit_broadcast return value error bug") Reported-by: Weiming Shi Signed-off-by: Xiang Mei Link: https://patch.msgid.link/20260326075553.3960562-1-xmei5@asu.edu Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin Signed-off-by: Kevin Berry Signed-off-by: Greg Kroah-Hartman --- drivers/net/bonding/bond_main.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index 114ebaa284da..6484ba1ab14c 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -5280,18 +5280,22 @@ static netdev_tx_t bond_xmit_broadcast(struct sk_buff *skb, struct net_device *bond_dev) { struct bonding *bond = netdev_priv(bond_dev); - struct slave *slave = NULL; - struct list_head *iter; + struct bond_up_slave *slaves; bool xmit_suc = false; bool skb_used = false; + int slaves_count, i; - bond_for_each_slave_rcu(bond, slave, iter) { + slaves = rcu_dereference(bond->all_slaves); + + slaves_count = slaves ? READ_ONCE(slaves->count) : 0; + for (i = 0; i < slaves_count; i++) { + struct slave *slave = slaves->arr[i]; struct sk_buff *skb2; if (!(bond_slave_is_up(slave) && slave->link == BOND_LINK_UP)) continue; - if (bond_is_last_slave(bond, slave)) { + if (i + 1 == slaves_count) { skb2 = skb; skb_used = true; } else { base-commit: 258cf62a6dfde3c6a39d120a56a298f2ed6a8901 -- 2.54.0.563.g4f69b47b94-goog