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 B6FE430100E; Mon, 18 Aug 2025 10:53:53 +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=1755514436; cv=none; b=u0Ag04Zl8H+WGqN1EznOb1/YZFtf3Q7i17cbeswqwMbOQI1DfsEqDTd7OYHFBSGkS/aTASSIk3ICzQDrydRF7b7nR+vsH+mOwWwBf8bU5xs0CwPMzxuLqlzubraDgFwF830gplFAIUuAj/+pjC66kOIYLJ97bYBnC1Oo3M2hcNM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755514436; c=relaxed/simple; bh=bdkGFGntJn6b9/DexCBKcDKT9nz79mQibMj1XFOZbAI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=VGnSIcWusYB7agiqeRG1GmcUeE3GYtv7Cg4IlQ923yP28LTwvEij7+XvLCykNs+6OV4nrt346b7V9JGZ2vtY70QNWEXtye5npxbbg+WMTRBVUmcezqFyaSE8rCnfnNnffCKSzRw2RY6mnD+ZaoTPXhLw1jCCJfxJzhw5DOlB00g= 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=Tj/Bm0j2; 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="Tj/Bm0j2" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1755514424; h=Date:From:To:Subject:Message-ID:MIME-Version:Content-Type; bh=UC+BNZzpQ+2R/7vUVL670jKwVT1hX1AhqBX1uis4yPM=; b=Tj/Bm0j27okO4rsi+mbgGvlrgwicdRTNTF/uIGXmKv0ArGiJOkb0XWoGVxfywZrPPtZlac6pQHsC6h8FwElRGkkBtVU39vhQTSwlZGF7o42CEFjVgT+jm9wGkMgZNChGARmk8uwCKrbLnCLPnV7q4PtAGeszYVNY/eQrY57BIkc= Received: from localhost(mailfrom:dust.li@linux.alibaba.com fp:SMTPD_---0Wm-j9fQ_1755514423 cluster:ay36) by smtp.aliyun-inc.com; Mon, 18 Aug 2025 18:53:43 +0800 Date: Mon, 18 Aug 2025 18:53:43 +0800 From: Dust Li To: "D. Wythe" , Mahanta.Jambigi@ibm.com, Sidraya.Jayagond@ibm.com, wenjia@linux.ibm.com, wintera@linux.ibm.com, tonylu@linux.alibaba.com, guwen@linux.alibaba.com Cc: kuba@kernel.org, davem@davemloft.net, netdev@vger.kernel.org, linux-s390@vger.kernel.org, linux-rdma@vger.kernel.org, pabeni@redhat.com, edumazet@google.com, jaka@linux.ibm.com Subject: Re: [PATCH net] net/smc: fix UAF on smcsk after smc_listen_out() Message-ID: Reply-To: dust.li@linux.alibaba.com References: <20250818054618.41615-1-alibuda@linux.alibaba.com> Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250818054618.41615-1-alibuda@linux.alibaba.com> On 2025-08-18 13:46:18, D. Wythe wrote: >BPF CI testing report a UAF issue: > > [ 16.446633] BUG: kernel NULL pointer dereference, address: 000000000000003 0 > [ 16.447134] #PF: supervisor read access in kernel mod e > [ 16.447516] #PF: error_code(0x0000) - not-present pag e > [ 16.447878] PGD 0 P4D 0 > [ 16.448063] Oops: Oops: 0000 [#1] PREEMPT SMP NOPT I > [ 16.448409] CPU: 0 UID: 0 PID: 9 Comm: kworker/0:1 Tainted: G OE 6.13.0-rc3-g89e8a75fda73-dirty #4 2 > [ 16.449124] Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODUL E > [ 16.449502] Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/201 4 > [ 16.450201] Workqueue: smc_hs_wq smc_listen_wor k > [ 16.450531] RIP: 0010:smc_listen_work+0xc02/0x159 0 > [ 16.452158] RSP: 0018:ffffb5ab40053d98 EFLAGS: 0001024 6 > [ 16.452526] RAX: 0000000000000001 RBX: 0000000000000002 RCX: 000000000000030 0 > [ 16.452994] RDX: 0000000000000280 RSI: 00003513840053f0 RDI: 000000000000000 0 > [ 16.453492] RBP: ffffa097808e3800 R08: ffffa09782dba1e0 R09: 000000000000000 5 > [ 16.453987] R10: 0000000000000000 R11: 0000000000000000 R12: ffffa0978274640 0 > [ 16.454497] R13: 0000000000000000 R14: 0000000000000000 R15: ffffa09782d4092 0 > [ 16.454996] FS: 0000000000000000(0000) GS:ffffa097bbc00000(0000) knlGS:000000000000000 0 > [ 16.455557] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003 3 > [ 16.455961] CR2: 0000000000000030 CR3: 0000000102788004 CR4: 0000000000770ef 0 > [ 16.456459] PKRU: 5555555 4 > [ 16.456654] Call Trace : > [ 16.456832] > [ 16.456989] ? __die+0x23/0x7 0 > [ 16.457215] ? page_fault_oops+0x180/0x4c 0 > [ 16.457508] ? __lock_acquire+0x3e6/0x249 0 > [ 16.457801] ? exc_page_fault+0x68/0x20 0 > [ 16.458080] ? asm_exc_page_fault+0x26/0x3 0 > [ 16.458389] ? smc_listen_work+0xc02/0x159 0 > [ 16.458689] ? smc_listen_work+0xc02/0x159 0 > [ 16.458987] ? lock_is_held_type+0x8f/0x10 0 > [ 16.459284] process_one_work+0x1ea/0x6d 0 > [ 16.459570] worker_thread+0x1c3/0x38 0 > [ 16.459839] ? __pfx_worker_thread+0x10/0x1 0 > [ 16.460144] kthread+0xe0/0x11 0 > [ 16.460372] ? __pfx_kthread+0x10/0x1 0 > [ 16.460640] ret_from_fork+0x31/0x5 0 > [ 16.460896] ? __pfx_kthread+0x10/0x1 0 > [ 16.461166] ret_from_fork_asm+0x1a/0x3 0 > [ 16.461453] > [ 16.461616] Modules linked in: bpf_testmod(OE) [last unloaded: bpf_testmod(OE) ] > [ 16.462134] CR2: 000000000000003 0 > [ 16.462380] ---[ end trace 0000000000000000 ]--- > [ 16.462710] RIP: 0010:smc_listen_work+0xc02/0x1590 > >The direct cause of this issue is that after smc_listen_out_connected(), >newclcsock->sk may be NULL since it will releases the smcsk. Therefore, >if the application closes the socket immediately after accept, >newclcsock->sk can be NULL. A possible execution order could be as >follows: > >smc_listen_work | userspace >----------------------------------------------------------------- >lock_sock(sk) | >smc_listen_out_connected() | >| \- smc_listen_out | >| | \- release_sock | > | |- sk->sk_data_ready() | > | fd = accept(); > | close(fd); > | \- socket->sk = NULL; >/* newclcsock->sk is NULL now */ >SMC_STAT_SERV_SUCC_INC(sock_net(newclcsock->sk)) > >Since smc_listen_out_connected() will not fail, simply swapping the order >of the code can easily fix this issue. > >Fixes: 3b2dec2603d5 ("net/smc: restructure client and server code in af_smc") >Signed-off-by: D. Wythe >Reviewed-by: Guangguan Wang >Reviewed-by: Alexandra Winter Reviewed-by: Dust Li Best regards, Dust >--- > net/smc/af_smc.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > >diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c >index 9311c38f7abe..e0e48f24cd61 100644 >--- a/net/smc/af_smc.c >+++ b/net/smc/af_smc.c >@@ -2568,8 +2568,9 @@ static void smc_listen_work(struct work_struct *work) > goto out_decl; > } > >- smc_listen_out_connected(new_smc); > SMC_STAT_SERV_SUCC_INC(sock_net(newclcsock->sk), ini); >+ /* smc_listen_out() will release smcsk */ >+ smc_listen_out_connected(new_smc); > goto out_free; > > out_unlock: >-- >2.45.0 >