From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f202.google.com (mail-pf1-f202.google.com [209.85.210.202]) (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 F4142DDA9 for ; Tue, 28 Apr 2026 16:32:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777393935; cv=none; b=p/6RwSbCEOasQbPZVIr7fK/RPcLIaqVo8BBSCkFzfqPMyM5yNkrT018qDGoi055pd0hm4AECbCn8F6YMzDPDl2N+mwDhOWJyZlsXVSLHr6PcmoiraiDtY4hp5j+UUEUg4grXoqtMYOl3q47GV4i4fiBSvHigSerelavsjE6b540= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777393935; c=relaxed/simple; bh=+sU4XCLUoFB8fRhNO3eN/ZXWBYJUzMMzukc44pMotiY=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=CMa2bwCKFZEL3RSUnLfxNcf9uMmJLZiS4+bn7O50mbNkcCbdh90PpQA8ZtNFaI7H2xtCqQGqmFwb5v+nhizPVw7sgs8viGca50CZTTNS46cWDSo54b0KSbP7oY6VBx3nTUt5wc/t+GmEPkICcle9FQy+uQT1eFNacwop7FEsbEc= 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=B9Tf/5O4; arc=none smtp.client-ip=209.85.210.202 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="B9Tf/5O4" Received: by mail-pf1-f202.google.com with SMTP id d2e1a72fcca58-82f2138a9e0so7408703b3a.3 for ; Tue, 28 Apr 2026 09:32:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1777393933; x=1777998733; 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=V6ZXXHA8w3KYlTHJv6KyoGFLgNYb30vzsCCTHpgraVA=; b=B9Tf/5O4UGEItBegrb9pldUKaBygiYb0QJ+pLq2K++4Rlo0nD5QcExPZcJZqMDYl5g BfD6eiJFvZhwdMd6y6PZuHokU1YTdHaBanA3qd6x0/UJmCQtNqC0xkNWlzQD5JJrZ7VU uNdahc3JGQp9vS2mPqhtx2OoQqMfeaD6ImmCOmu9J2xsIpINEUFZZBWvH705zsA3sVvJ 5NkySuLFoCNK3LHPOm4ZjHH7ehE6q4Nei2dMSxUTdFJzctSGg14k+9xl326uG0eqWOes AMcqfHrXq6UKMupKFiiH3lG0gXNbLz4VeW+cK1PHExa2ma5dqQ6VnbaO0vZaG0t56fKk fhBg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1777393933; x=1777998733; 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=V6ZXXHA8w3KYlTHJv6KyoGFLgNYb30vzsCCTHpgraVA=; b=WSh97eTmyXp+qyHzEsUw7IsKBDIYNT7H7aOCJ0rNeDyLZZc9yvgekZFhZN1Ui2Urcd sznq9Dy4Sn3comA/D4k2/qqltK9aSL0mdo3NajcxwBw21ItdhEUAsy75un3vWi4AXEuJ LGH/EeGzCVb0C04L5YmEfond6ZH82r2La7LIzrLvlg2Tn560LDAdaBoblmOg/R089udm I3KmGN2d4TQQjafib7Tyjwe/tMxSBG0XTfzsYUfpr0rTM8FhGAw9GFAU3Y/o1N18fFRa Kg+tDaWxOOy0UWUAxHxqM86Ji1uD+XVIAgGx01yvipHBd2zHWfdZ5hGXDrj99NDTgqxQ IO1g== X-Forwarded-Encrypted: i=1; AFNElJ/D1Fpm/KlmjzbVzKXgwUnm/AamzNDiNR8XL7qUpDA0EptNiQx+54C3aE7RHfO6VSMQDoQ9grg=@vger.kernel.org X-Gm-Message-State: AOJu0Yxh6Cch17Kp5xxx93pUbLY+PGBX8g7W7QY5XDyxP4l81NM55Acu v7gwe/EdSu8GSQIU6JSu30MQO/2c9HgDVGNQbPr8fFjaUwd6qxH37FcpLyx3pBkP3oWzRqnxE6P p4nNTTTB7Kw== X-Received: from pfjd1.prod.google.com ([2002:a05:6a00:2441:b0:82f:af79:9f3]) (user=kpberry job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:2da8:b0:82f:9300:cc44 with SMTP id d2e1a72fcca58-834ea32b5cemr42118b3a.8.1777393933101; Tue, 28 Apr 2026 09:32:13 -0700 (PDT) Date: Tue, 28 Apr 2026 16:32:03 +0000 In-Reply-To: <20260428104138.reply-bonding-6.12@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260428104138.reply-bonding-6.12@kernel.org> X-Mailer: git-send-email 2.54.0.545.g6539524ca2-goog Message-ID: <20260428163203.796681-1-kpberry@google.com> Subject: [PATCH v2] net: bonding: fix use-after-free in bond_xmit_broadcast() From: Kevin Berry To: xmei5@asu.edu Cc: bestswngs@gmail.com, chenglongtang@google.com, joneslee@google.com, kpberry@google.com, pabeni@redhat.com, rnj@google.com, stable@vger.kernel.org Content-Type: text/plain; charset="UTF-8" From: Xiang Mei 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: Kevin Berry --- drivers/net/bonding/bond_main.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index 5035cfa74f1a..9f1a189d46f1 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -5326,14 +5326,21 @@ static netdev_tx_t bond_xmit_broadcast(struct sk_buff *skb, struct list_head *iter; bool xmit_suc = false; bool skb_used = false; + int slaves_count, i = 0; + slaves_count = READ_ONCE(bond->slave_cnt); bond_for_each_slave_rcu(bond, slave, iter) { struct sk_buff *skb2; + bool is_last; + + if (++i > slaves_count) + break; + is_last = (i == slaves_count); if (!(bond_slave_is_up(slave) && slave->link == BOND_LINK_UP)) continue; - if (bond_is_last_slave(bond, slave)) { + if (is_last) { skb2 = skb; skb_used = true; } else { base-commit: c286ea5e62389897291fa742d2bb909ecc9ef2d0 -- 2.54.0.545.g6539524ca2-goog