From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) (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 AAFFE7F484; Wed, 19 Jun 2024 12:31:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.130 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718800291; cv=none; b=UPB0VVOXMfkH6EuAom4t+yDE2L7jX1p7vbk44FprnpIdWChRESiRAXJO71+PYUewDLqYf6QwIPR4DPiwfA+Y1AQPAMlPgxqYaNi9oB3HTX5bTg7Ex8dXe+09IPpjj6D8LWG3BgxvDN3C+aOh4Y/bmrkMDgWsq2Z4xp214W96plk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718800291; c=relaxed/simple; bh=wpMOkSoPBVIQ3ZosCdP2tRyslpQaJDB9yAagwaWj1xQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=CYCO65GdX4g70xieZs9fovUnfd7EmKSNuXvXF+mH6yli3+4ngv17GINPOA/IZoXWR6gBkj0HDeSpfTHfGM2BH4GnnewPcBhQSuetj5w9QHq/li83413ZaAofedXbVPAPDNZp7Pi1gVr/IQdPv8n2j3iXEPYsfyPi8t7PzTrvODw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=lZxOR0wF; arc=none smtp.client-ip=115.124.30.130 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="lZxOR0wF" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1718800285; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=B5RdL+8cB/GSNge3uIMvi0Jzb3nSy+m4P9mjkS+8pFk=; b=lZxOR0wFsEHkZPk9z7sYLJwIGZW+Vecin50dwXczyEb3HhMGdFCDbr5LyZQpe4iG2vVkuj8YebDnXrr1ycoWD9/IXcDu6/WEMY2njvrWntJnRuNWKoyJzrQ6eji/1xXJI2P1ZoAcGkfbMcwsEsFTUhYxE1zrQsqA/kNgeUFnKzs= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R191e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033037067111;MF=alibuda@linux.alibaba.com;NM=1;PH=DS;RN=12;SR=0;TI=SMTPD_---0W8oFJ7S_1718800283; Received: from 30.221.146.77(mailfrom:alibuda@linux.alibaba.com fp:SMTPD_---0W8oFJ7S_1718800283) by smtp.aliyun-inc.com; Wed, 19 Jun 2024 20:31:24 +0800 Message-ID: Date: Wed, 19 Jun 2024 20:31:23 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net v3] net: do not leave a dangling sk pointer, when socket creation fails To: Ignat Korchagin , "David S. Miller" , David Ahern , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Florent Revest , kernel-team@cloudflare.com, Kuniyuki Iwashima , stable@vger.kernel.org References: <20240617210205.67311-1-ignat@cloudflare.com> Content-Language: en-US From: "D. Wythe" In-Reply-To: <20240617210205.67311-1-ignat@cloudflare.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 6/18/24 5:02 AM, Ignat Korchagin wrote: > It is possible to trigger a use-after-free by: > * attaching an fentry probe to __sock_release() and the probe calling the > bpf_get_socket_cookie() helper > * running traceroute -I 1.1.1.1 on a freshly booted VM > > A KASAN enabled kernel will log something like below (decoded and stripped): > ================================================================== > 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) > Read of size 8 at addr ffff888007110dd8 by task traceroute/299 > > CPU: 2 PID: 299 Comm: traceroute Tainted: G E 6.10.0-rc2+ #2 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 > Call Trace: > > dump_stack_lvl (lib/dump_stack.c:117 (discriminator 1)) > print_report (mm/kasan/report.c:378 mm/kasan/report.c:488) > ? __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) > kasan_report (mm/kasan/report.c:603) > ? __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) > kasan_check_range (mm/kasan/generic.c:183 mm/kasan/generic.c:189) > __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) > 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) > bpf_prog_875642cf11f1d139___sock_release+0x6e/0x8e > bpf_trampoline_6442506592+0x47/0xaf > __sock_release (net/socket.c:652) > __sock_create (net/socket.c:1601) > ... > Allocated by task 299 on cpu 2 at 78.328492s: > kasan_save_stack (mm/kasan/common.c:48) > kasan_save_track (mm/kasan/common.c:68) > __kasan_slab_alloc (mm/kasan/common.c:312 mm/kasan/common.c:338) > kmem_cache_alloc_noprof (mm/slub.c:3941 mm/slub.c:4000 mm/slub.c:4007) > sk_prot_alloc (net/core/sock.c:2075) > sk_alloc (net/core/sock.c:2134) > inet_create (net/ipv4/af_inet.c:327 net/ipv4/af_inet.c:252) > __sock_create (net/socket.c:1572) > __sys_socket (net/socket.c:1660 net/socket.c:1644 net/socket.c:1706) > __x64_sys_socket (net/socket.c:1718) > do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83) > entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) > > Freed by task 299 on cpu 2 at 78.328502s: > kasan_save_stack (mm/kasan/common.c:48) > kasan_save_track (mm/kasan/common.c:68) > kasan_save_free_info (mm/kasan/generic.c:582) > poison_slab_object (mm/kasan/common.c:242) > __kasan_slab_free (mm/kasan/common.c:256) > kmem_cache_free (mm/slub.c:4437 mm/slub.c:4511) > __sk_destruct (net/core/sock.c:2117 net/core/sock.c:2208) > inet_create (net/ipv4/af_inet.c:397 net/ipv4/af_inet.c:252) > __sock_create (net/socket.c:1572) > __sys_socket (net/socket.c:1660 net/socket.c:1644 net/socket.c:1706) > __x64_sys_socket (net/socket.c:1718) > do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83) > 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, which may already attached the > reference to the sk object with sock_init_data(). > > 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 v3: > * re-added KASAN repro steps to the commit message (somehow stripped in v2) > * stripped timestamps and thread id from the KASAN splat > * removed comment from the code (commit message should be enough) > > 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 > > net/core/sock.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/net/core/sock.c b/net/core/sock.c > index 8629f9aecf91..100e975073ca 100644 > --- a/net/core/sock.c > +++ b/net/core/sock.c > @@ -3742,6 +3742,9 @@ void sk_common_release(struct sock *sk) > > sk->sk_prot->unhash(sk); > > + 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 Reviewed-by: D. Wythe A small tip: It seems that you might have missed CCing some maintainers, using scripts/get_maintainer.pl "Your patch" can help you avoid this issue again. D. Wythe