From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-fw-6002.amazon.com (smtp-fw-6002.amazon.com [52.95.49.90]) (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 D6BF3F9F7; Mon, 17 Jun 2024 20:31:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=52.95.49.90 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718656267; cv=none; b=tcJihynhH1FDeHKMK7D72Lw++D77UVnMg/ZQcev/K4nQ4BS7eiXFNzXdfsgh8tpvElHcz8VomKvFIi98w0dVd2hbmpcvzynnWyg2v+khnnKhotKsrg8rQC9DHy++oSIxmg4AMctJ7BU5lwOh0wQGAp7d0GwUqZT3BqlfDsE1ims= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718656267; c=relaxed/simple; bh=WcKrT/rg+wQ0qVdpNz/1++mnHbo87dnDF65GYYAYSNI=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=mIg9xJhz7iNJaRnt8CBavP77ijKFkuyLKByXcWUrqE0jQA2twKvTlVxzQv+I7G5hpFtMBCcfAkYlJsNzDSrxswTkgyXkxbzUKKWK8W/qH23W/X5MUm6K8pTQoTVkAmiXDZ8Q43d6b4GDkUszDRGNFLlq1B8YOPsUno8ggjlJACg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com; spf=pass smtp.mailfrom=amazon.co.jp; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b=F/QoPec2; arc=none smtp.client-ip=52.95.49.90 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.co.jp Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="F/QoPec2" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1718656267; x=1750192267; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=VlPB0O2dnR3nvk4Kh7euEZXylj1IyW7hKA8b3eERaK8=; b=F/QoPec2xaymIpPaUedQ3+yerPiS/tt2Qi+enaqP3Q4jh6zMfjhG81BY 8rnz+z/FUIAPDDwTStj9MWT/V2uTSQtk6Et7zA25TqH4M4rkj8dUyfI3D qTix1at5YTGJYKJqnA0v/zlswe81GSn/ZaHRMDx1ckJbikHs58fSvSgDR Q=; X-IronPort-AV: E=Sophos;i="6.08,245,1712620800"; d="scan'208";a="413945634" Received: from iad12-co-svc-p1-lb1-vlan3.amazon.com (HELO smtpout.prod.us-west-2.prod.farcaster.email.amazon.dev) ([10.43.8.6]) by smtp-border-fw-6002.iad6.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jun 2024 20:31:03 +0000 Received: from EX19MTAUWC001.ant.amazon.com [10.0.7.35:35396] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.61.128:2525] with esmtp (Farcaster) id c6dc14fa-53e4-4974-a338-b2cb36969ba5; Mon, 17 Jun 2024 20:31:01 +0000 (UTC) X-Farcaster-Flow-ID: c6dc14fa-53e4-4974-a338-b2cb36969ba5 Received: from EX19D004ANA001.ant.amazon.com (10.37.240.138) by EX19MTAUWC001.ant.amazon.com (10.250.64.174) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.34; Mon, 17 Jun 2024 20:31:01 +0000 Received: from 88665a182662.ant.amazon.com (10.187.171.38) by EX19D004ANA001.ant.amazon.com (10.37.240.138) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.34; Mon, 17 Jun 2024 20:30:58 +0000 From: Kuniyuki Iwashima To: CC: , , , , , , , , , , Subject: Re: [PATCH net v2] net: do not leave a dangling sk pointer, when socket creation fails Date: Mon, 17 Jun 2024 13:30:50 -0700 Message-ID: <20240617203050.84843-1-kuniyu@amazon.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20240617195934.64810-1-ignat@cloudflare.com> References: <20240617195934.64810-1-ignat@cloudflare.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: EX19D045UWA001.ant.amazon.com (10.13.139.83) To EX19D004ANA001.ant.amazon.com (10.37.240.138) From: Ignat Korchagin Date: Mon, 17 Jun 2024 20:59:34 +0100 > A KASAN enabled kernel will log something like below (decoded and stripped): > [ 78.328507][ T299] ================================================================== > [ 78.329018][ T299] BUG: KASAN: slab-use-after-free in __sock_gen_cookie (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2583 ./include/linux/atomic/atomic-instrumented.h:1611 net/core/sock_diag.c:29) > [ 78.329366][ T299] Read of size 8 at addr ffff888007110dd8 by task traceroute/299 > [ 78.329366][ T299] > [ 78.329366][ T299] CPU: 2 PID: 299 Comm: traceroute Tainted: G E 6.10.0-rc2+ #2 > [ 78.329366][ T299] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 > [ 78.329366][ T299] Call Trace: > [ 78.329366][ T299] > [ 78.329366][ T299] dump_stack_lvl (lib/dump_stack.c:117 (discriminator 1)) > [ 78.329366][ T299] print_report (mm/kasan/report.c:378 mm/kasan/report.c:488) > [ 78.329366][ T299] ? __sock_gen_cookie (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2583 ./include/linux/atomic/atomic-instrumented.h:1611 net/core/sock_diag.c:29) > [ 78.329366][ T299] kasan_report (mm/kasan/report.c:603) > [ 78.329366][ T299] ? __sock_gen_cookie (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2583 ./include/linux/atomic/atomic-instrumented.h:1611 net/core/sock_diag.c:29) > [ 78.329366][ T299] kasan_check_range (mm/kasan/generic.c:183 mm/kasan/generic.c:189) > [ 78.329366][ T299] __sock_gen_cookie (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2583 ./include/linux/atomic/atomic-instrumented.h:1611 net/core/sock_diag.c:29) > [ 78.329366][ T299] bpf_get_socket_ptr_cookie (./arch/x86/include/asm/preempt.h:94 ./include/linux/sock_diag.h:42 net/core/filter.c:5094 net/core/filter.c:5092) > [ 78.329366][ T299] bpf_prog_875642cf11f1d139___sock_release+0x6e/0x8e > [ 78.329366][ T299] bpf_trampoline_6442506592+0x47/0xaf > [ 78.329366][ T299] __sock_release (net/socket.c:652) > [ 78.329366][ T299] __sock_create (net/socket.c:1601) > ... > [ 78.329366][ T299] Allocated by task 299 on cpu 2 at 78.328492s: > [ 78.329366][ T299] kasan_save_stack (mm/kasan/common.c:48) > [ 78.329366][ T299] kasan_save_track (mm/kasan/common.c:68) > [ 78.329366][ T299] __kasan_slab_alloc (mm/kasan/common.c:312 mm/kasan/common.c:338) > [ 78.329366][ T299] kmem_cache_alloc_noprof (mm/slub.c:3941 mm/slub.c:4000 mm/slub.c:4007) > [ 78.329366][ T299] sk_prot_alloc (net/core/sock.c:2075) > [ 78.329366][ T299] sk_alloc (net/core/sock.c:2134) > [ 78.329366][ T299] inet_create (net/ipv4/af_inet.c:327 net/ipv4/af_inet.c:252) > [ 78.329366][ T299] __sock_create (net/socket.c:1572) > [ 78.329366][ T299] __sys_socket (net/socket.c:1660 net/socket.c:1644 net/socket.c:1706) > [ 78.329366][ T299] __x64_sys_socket (net/socket.c:1718) > [ 78.329366][ T299] do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83) > [ 78.329366][ T299] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) > [ 78.329366][ T299] > [ 78.329366][ T299] Freed by task 299 on cpu 2 at 78.328502s: > [ 78.329366][ T299] kasan_save_stack (mm/kasan/common.c:48) > [ 78.329366][ T299] kasan_save_track (mm/kasan/common.c:68) > [ 78.329366][ T299] kasan_save_free_info (mm/kasan/generic.c:582) > [ 78.329366][ T299] poison_slab_object (mm/kasan/common.c:242) > [ 78.329366][ T299] __kasan_slab_free (mm/kasan/common.c:256) > [ 78.329366][ T299] kmem_cache_free (mm/slub.c:4437 mm/slub.c:4511) > [ 78.329366][ T299] __sk_destruct (net/core/sock.c:2117 net/core/sock.c:2208) > [ 78.329366][ T299] inet_create (net/ipv4/af_inet.c:397 net/ipv4/af_inet.c:252) > [ 78.329366][ T299] __sock_create (net/socket.c:1572) > [ 78.329366][ T299] __sys_socket (net/socket.c:1660 net/socket.c:1644 net/socket.c:1706) > [ 78.329366][ T299] __x64_sys_socket (net/socket.c:1718) > [ 78.329366][ T299] do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83) > [ 78.329366][ T299] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) > > Fix this by clearing the struct socket reference in sk_common_release() to cover > all protocol families create functions. > > Fixes: c5dbb89fc2ac ("bpf: Expose bpf_get_socket_cookie to tracing programs") > Suggested-by: Kuniyuki Iwashima > Signed-off-by: Ignat Korchagin > Cc: stable@vger.kernel.org > Link: https://lore.kernel.org/netdev/20240613194047.36478-1-kuniyu@amazon.com/T/ > --- > Changes in v2: > * moved the NULL-ing of the socket reference to sk_common_release() (as > suggested by Kuniyuki Iwashima) > * trimmed down the KASAN report in the commit message to show only relevant > info It seems the most important repro was lost. I'd like to keep that in the commit message so that we can easily understand the Fixes: tag and how the issue happens. While at it, could you remove the timestamp and thread id in KASAN splat ? > > net/core/sock.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/net/core/sock.c b/net/core/sock.c > index 8629f9aecf91..575af557c46b 100644 > --- a/net/core/sock.c > +++ b/net/core/sock.c > @@ -3742,6 +3742,17 @@ void sk_common_release(struct sock *sk) > > sk->sk_prot->unhash(sk); > > + /* > + * struct net_proto_family create functions like inet_create() or nit: This should be netdev style: /* struct net_proto_family ... * ... */ See: Documentation/process/maintainer-netdev.rst But I think the comment is not needed here if the commit message has * KASAN splat * How the problem happens * run bpf_get_socket_cookie() in __sock_release() * What the problem is * UAF happens if pf->create() fails after calling sock_init_data() , we can just git-blame the change below. Thanks! > + * inet6_create() have an error path, which call this function. This sk > + * may have already been associated with a struct socket, so ensure to > + * clear this reference not to leave a dangling pointer in the > + * struct socket instance. > + */ > + > + if (sk->sk_socket) > + sk->sk_socket->sk = NULL; > + > /* > * In this point socket cannot receive new packets, but it is possible > * that some packets are in flight because some CPU runs receiver and > -- > 2.39.2