From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qt1-f173.google.com (mail-qt1-f173.google.com [209.85.160.173]) (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 3474D4502F for ; Fri, 19 Sep 2025 14:46:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758293218; cv=none; b=M3xV7GcY/x4rcIACDbfrnSPCMTGvEuFtOe+vPAdFAjMrid4rAPTZT8umA12wHYpveF2mJMNfZY7a4WlrPGZstWdUXXxSrn384Qs6iDd0a4FAxzxOHHKXYnJE2rfI5ChpP3wpSN6bj/ZAefj/IzDoN/02vsJnksecn5WdfPcxHj4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758293218; c=relaxed/simple; bh=rMzpqLEOEhteINqvc5dyan4rtMP3A9UTuyesjbI13LA=; h=Date:From:To:Cc:Message-ID:In-Reply-To:References:Subject: Mime-Version:Content-Type; b=eDVzfG76JkwdyNC5IFGj+vlJjzRlsdweKg9m3arbTYm8p63wXZP2P0HnBoaYxbsfc/xvPu70Yh12lLHv5E9O3OTrlq6A+BNIB1ppcEnxp0e3uat8zqXHxHyRR7DP8B8IY4U4RqlWUqzrCZo5ztTI3+UX5V8wuqdRs6uhBoLkrVM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=A4nXpIPa; arc=none smtp.client-ip=209.85.160.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="A4nXpIPa" Received: by mail-qt1-f173.google.com with SMTP id d75a77b69052e-4b79773a389so22771431cf.1 for ; Fri, 19 Sep 2025 07:46:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1758293216; x=1758898016; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:subject:references :in-reply-to:message-id:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=BTCj+e/VtZ/D02X1h15E6NfB/hO2pboJylbEQXWpz8E=; b=A4nXpIPa+2BhjVsulZSLhLIPr3E+ZFHQUuJRXnK3toMeDpl/tIJlbRWgTKMiRShSu2 wcSH2+RapQp3ncIktiuybEZ9Nd99ZyBKhUaqw9wrt8zq/woRd5GRzwkukmR7t0Lz3e02 eItFjH3S0UmGQltEJH4/lg14WuxXQMfzicM/FysACFU1VzYzcGy4Tvy81wv7XbqcGen/ OQKgF9Yyrfvdl9YhVTub/urvZM12PjLLND/k1napHlkkLWnjYuYFlGyeMXKxnmooxdro KYxQFg36h3oqwaABM4TdY73aYeSXG1qARFfVZDZHymcn5P90PYs3bB7cJ91MWjahe0nb ykBA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1758293216; x=1758898016; h=content-transfer-encoding:mime-version:subject:references :in-reply-to:message-id:cc:to:from:date:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=BTCj+e/VtZ/D02X1h15E6NfB/hO2pboJylbEQXWpz8E=; b=MlbmdNTWE8Oo6Ltd5mRFzeBWFAsNYXdhVvWvQ9yqWE+TfC4MthUVIWFzb11gBbuS/e LCboGyfI9Yi6Rn5pfB8m9+iD00/EGaI+DP7WKTeEYwpLcZjaaMypz3FX8YjjfNaWg1B5 2QhqrqFpj/leZ0jB2y+bw/bMjd03fH/rYcOvMSkb/89ciMoOPZGlwZlYuqRBSv68EOR6 w2TA4Bpdg5wn2kGxLg29t6PCgs5bKni7npyQNBayvjJYtNDaiszmR49KTUVCSYYzlCl1 cReMHcKHJ7HnbGtvMaJvdT9wukZZwz4IhAA2MGuGtMPRXIoIUoB7T8QBchOeVV2P1ve3 WDcg== X-Forwarded-Encrypted: i=1; AJvYcCVIBo4HlL1jAX4vbLP/EA+YaaxpMfdQmdhwaKydSVnYXitVwyvvLEwtmFOaGVw6hBS773vyzVOSuMFddZk=@vger.kernel.org X-Gm-Message-State: AOJu0YzZDQGi/FTw5PEek/68VfQFTod5skXpyIgwX1eICYcTRG6H3E/y 5Ka78+YvHkdQC9YHlQyGVZ4EQ9aApWDAEZ9aVLNF/Cj7fDgc7vl3Pj4/+a3wfA== X-Gm-Gg: ASbGncsYiev4ZkvZbFQuP+eoI6ipT0cUSmMwVuvBHZ2rWlttVJEXBsD0kzFczUtpXv5 9IYuJmd6Zb7GSRGU5/nEBbiP8SObvZYd6sZlQWjzqHEiyR5CL416uvJR4agGqA+Uyx1InXxcRSw 0xkmnx05RJS5ylgr8xvIgOBs0MB5ybYQdMg9eoXyEUR9bNkJdB4ngrNplT2tuEe6YFw1/px5Npl qiVOGlCYUJmRk8aBd7U/7npJHozMlIHSxAmJGNJagtH6bkWzoWmPhZi+AGSnk5z6hQZ+k5DQKbB 8Tmv9GLgpAKAM3nmAreH2qBT//S3P5ft4iZ1c6CCSIvkZrGZ8MVUmY/+WMq8j0R7+SGIpZupfbs q4jJMJ1xZTVzCJn16KVkDX6kMBQf3qysGR01WNfuvyqA8nlG4EMVnhJVgda3WNIj6O51QOkRAzU eNvg== X-Google-Smtp-Source: AGHT+IEFvwYYDWYJDrNKDVvsS0tm4PJF42EUcN3g1p4ngNtR8j2nRJk0TdRdJI0JYwklpBYJ2GKC1A== X-Received: by 2002:a05:622a:5444:b0:4c0:cab7:978 with SMTP id d75a77b69052e-4c0cab70addmr15501021cf.29.1758293215746; Fri, 19 Sep 2025 07:46:55 -0700 (PDT) Received: from gmail.com (141.139.145.34.bc.googleusercontent.com. [34.145.139.141]) by smtp.gmail.com with UTF8SMTPSA id d75a77b69052e-4bda279ad7esm30915921cf.19.2025.09.19.07.46.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 19 Sep 2025 07:46:55 -0700 (PDT) Date: Fri, 19 Sep 2025 10:46:54 -0400 From: Willem de Bruijn To: Wang Liang , willemdebruijn.kernel@gmail.com, jasowang@redhat.com, andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com, sdf@fomichev.me, lorenzo@kernel.org, toke@redhat.com Cc: yuehaibing@huawei.com, zhangchangzhong@huawei.com, wangliang74@huawei.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org Message-ID: In-Reply-To: <20250917113919.3991267-1-wangliang74@huawei.com> References: <20250917113919.3991267-1-wangliang74@huawei.com> Subject: Re: [PATCH net] net: tun: Update napi->skb after XDP process Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Wang Liang wrote: > The syzbot report a UAF issue: > > BUG: KASAN: slab-use-after-free in skb_reset_mac_header include/linux/skbuff.h:3150 [inline] > BUG: KASAN: slab-use-after-free in napi_frags_skb net/core/gro.c:723 [inline] > BUG: KASAN: slab-use-after-free in napi_gro_frags+0x6e/0x1030 net/core/gro.c:758 > Read of size 8 at addr ffff88802ef22c18 by task syz.0.17/6079 > CPU: 0 UID: 0 PID: 6079 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) > Call Trace: > > dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 > print_address_description mm/kasan/report.c:378 [inline] > print_report+0xca/0x240 mm/kasan/report.c:482 > kasan_report+0x118/0x150 mm/kasan/report.c:595 > skb_reset_mac_header include/linux/skbuff.h:3150 [inline] > napi_frags_skb net/core/gro.c:723 [inline] > napi_gro_frags+0x6e/0x1030 net/core/gro.c:758 > tun_get_user+0x28cb/0x3e20 drivers/net/tun.c:1920 > tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:1996 > new_sync_write fs/read_write.c:593 [inline] > vfs_write+0x5c9/0xb30 fs/read_write.c:686 > ksys_write+0x145/0x250 fs/read_write.c:738 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > > Allocated by task 6079: > kasan_save_stack mm/kasan/common.c:47 [inline] > kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 > unpoison_slab_object mm/kasan/common.c:330 [inline] > __kasan_mempool_unpoison_object+0xa0/0x170 mm/kasan/common.c:558 > kasan_mempool_unpoison_object include/linux/kasan.h:388 [inline] > napi_skb_cache_get+0x37b/0x6d0 net/core/skbuff.c:295 > __alloc_skb+0x11e/0x2d0 net/core/skbuff.c:657 > napi_alloc_skb+0x84/0x7d0 net/core/skbuff.c:811 > napi_get_frags+0x69/0x140 net/core/gro.c:673 > tun_napi_alloc_frags drivers/net/tun.c:1404 [inline] > tun_get_user+0x77c/0x3e20 drivers/net/tun.c:1784 > tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:1996 > new_sync_write fs/read_write.c:593 [inline] > vfs_write+0x5c9/0xb30 fs/read_write.c:686 > ksys_write+0x145/0x250 fs/read_write.c:738 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > Freed by task 6079: > kasan_save_stack mm/kasan/common.c:47 [inline] > kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 > kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576 > poison_slab_object mm/kasan/common.c:243 [inline] > __kasan_slab_free+0x5b/0x80 mm/kasan/common.c:275 > kasan_slab_free include/linux/kasan.h:233 [inline] > slab_free_hook mm/slub.c:2422 [inline] > slab_free mm/slub.c:4695 [inline] > kmem_cache_free+0x18f/0x400 mm/slub.c:4797 > skb_pp_cow_data+0xdd8/0x13e0 net/core/skbuff.c:969 > netif_skb_check_for_xdp net/core/dev.c:5390 [inline] > netif_receive_generic_xdp net/core/dev.c:5431 [inline] > do_xdp_generic+0x699/0x11a0 net/core/dev.c:5499 > tun_get_user+0x2523/0x3e20 drivers/net/tun.c:1872 > tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:1996 > new_sync_write fs/read_write.c:593 [inline] > vfs_write+0x5c9/0xb30 fs/read_write.c:686 > ksys_write+0x145/0x250 fs/read_write.c:738 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > After commit e6d5dbdd20aa ("xdp: add multi-buff support for xdp running in > generic mode"), the original skb may be freed in skb_pp_cow_data() when > XDP program was attached, which was allocated in tun_napi_alloc_frags(). > However, the napi->skb still point to the original skb, update it after > XDP process. > > Reported-by: syzbot+64e24275ad95a915a313@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=64e24275ad95a915a313 > Fixes: e6d5dbdd20aa ("xdp: add multi-buff support for xdp running in generic mode") > Signed-off-by: Wang Liang Reviewed-by: Willem de Bruijn