From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=115.124.30.113 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792584792; b=Hv33oWnMHFbkHCz0ee8cYHj27pUVu/41060EC4ggNLiczXLqijgEu0H4H1vSbzN6bFsY WoQU6i0J27OSMhL2DWFDAMLzY9VaaFGQ0fT40IJthc9Tpi2J8L/GcamL4E+LkQAYz0pAj jdX8N0mUhAn1z1slOToKzF4lmUZy7yjRErgY524Lj7hHYDAKeauRjSd2XIE0hp7BBaEhF DXPcsxv6d4/eDv+URMvFuxfLlmrl6WytEPiDFJjl2c5GziDxZ5LdA9kPCc7GliD5/zinL 0hmF3EMIRyQ4svQN4TI2MEPgJ9GFDb++8ethnxpObdADfQiJ5TRa1zIwCnQoDiaBqBA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792584792; h=DMARC-Filter:DKIM-Signature:X-Alimail-AntiSpam:Received:Date:From:To: Cc:Subject:Message-ID:Reply-To:References:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; bh=qHrtSmupKaWVw2UfmtmjwnVbsnSdj5SnjRXClja/+Ms=; b=wV7P4rNBuYnD8bGx2eAdTAZVksnfw1JfcxEfMle62PSvwLSsT2iqL75KJd9fTFMdp/2m ssn/hkg3gxwgNXsnvrzSY50kxS+GFNTAdJw/HGzlDbhvc39FvNo+M/hIZ5GVJBwn0gRGF 5SJWmO3YIpdmPfk12oVC5L2zLhSY9EXik3isq28wyA/aAd2uqgmt/CrKpvmeTwjHhbiqZ XfBWPOK/HXpo79JWRrV0OOBmsMIg749+4TTgQXy6k+RP5NsAI51mTlyEgkRSyHGVi6YcI cIqSknTTDeYQphexdR7g6lnNJfbr7XZyUQVmAJGZ0ICgn6mq/ux1iivFtUWYO1SWhHA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass header.d=linux.alibaba.com header.i=@linux.alibaba.com header.a=rsa-sha256 header.s=default header.b="Z2I/WGBE"; arc=none smtp.remote-ip=115.124.30.113 Received: from out30-113.freemail.mail.aliyun.com (out30-113.freemail.mail.aliyun.com [115.124.30.113]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 30EDF606A31A; Wed, 21 Oct 2026 12:13:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 30EDF606A31A 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, unprotected) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.a=rsa-sha256 header.s=default header.b=Z2I/WGBE DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1792584787; h=Date:From:To:Subject:Message-ID:MIME-Version:Content-Type; bh=qHrtSmupKaWVw2UfmtmjwnVbsnSdj5SnjRXClja/+Ms=; b=Z2I/WGBEcLqV/0fiJzgZ0wLMP0Ki3XWG8rPiaM5Qw8eTgaRIEwTaB1PaISda5+asFw1nTol584goS70z2GNrFho4dLXcg4xNIA6XncLm4qeU7oLY0NVoTc4BTNgkgLBoiSwedt3wlqW+MRbD7gCCnOW7TWKKpzTNvNXW6BLpqRA= 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-contentspam011083073210;MF=dust.li@linux.alibaba.com;NM=1;PH=DS;RN=16;SR=0;TI=SMTPD_---0XDGOERK_1792584786; Received: from localhost(mailfrom:dust.li@linux.alibaba.com fp:SMTPD_---0XDGOERK_1792584786 cluster:ay36) by smtp.aliyun-inc.com; Wed, 21 Oct 2026 20:13:06 +0800 Date: Wed, 21 Oct 2026 20:13:05 +0800 From: Dust Li To: Chengfeng Ye , alibuda@linux.alibaba.com, sidraya@linux.ibm.com, mjambigi@linux.ibm.com, davem@davemloft.net, edumazet@kernel.org, kuba@kernel.org, pabeni@redhat.com Cc: tonylu@linux.alibaba.com, guwen@linux.alibaba.com, horms@kernel.org, linux-rdma@vger.kernel.org, linux-s390@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH net v3 2/3] net/smc: serialize early link group cleanup with termination Message-ID: Reply-To: dust.li@linux.alibaba.com References: <20261013091716.1210420-1-nicoyip.dev@gmail.com> <20261013091716.1210420-3-nicoyip.dev@gmail.com> X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261013091716.1210420-3-nicoyip.dev@gmail.com> On 2026-10-13 17:17:15, Chengfeng Ye wrote: >smc_lgr_cleanup_early() enters __smc_lgr_terminate() even when another >teardown path has already claimed lgr->freeing. Both callers can observe >lgr->terminating clear before either sets it, then tear down the same >link group, causing use-after-free and duplicate resource release. > > BUG: KASAN: use-after-free in __smc_lgr_terminate+0x393/0x3a0 > Write of size 1 at addr ffff8880bf2c0300 by task poc/106 > Call Trace: > __smc_lgr_terminate+0x393/0x3a0 > __smc_connect+0x2e3d/0x4930 > smc_connect+0x42c/0x580 > __sys_connect+0xfc/0x130 > __x64_sys_connect+0x6d/0xb0 > >Check freeing under the link group list lock before unlinking the group >or entering termination. The existing locked freeing transition then >claims exclusive teardown ownership; an early cleanup that loses the >claim leaves teardown to the existing owner and does not remove the group >from a device teardown's private list. > >Keep a temporary link group reference across smc_conn_free() and early >cleanup in smc_conn_abort(). Once the connection is unregistered, a >termination worker can finish without taking its socket lock. The extra >reference keeps the allocation alive until the ownership check returns. > >A new group is published before its first connection is registered. Hold >it before publication until registration or failed-registration cleanup >finishes. The reference keeps the allocation alive, but teardown can still >destroy the group's resources before registration. Take the list lock >around the freeing check and first registration, nesting conns_lock as in >the reuse path. Reject a group already claimed for teardown and clear >conn->lgr, since that connection never acquired a group reference. > >On success, acquire the connection reference before dropping the temporary >hold. A later terminator sees the registered connection and must acquire >its socket lock before removing it. On failure, keep the temporary hold >through early cleanup and then release it. Reused groups retain their >existing reference protocol. > >This depends on "net/smc: serialize link group free work scheduling" for >the standalone freeing bool and the locked early-cleanup transition. > >Fixes: f9aab6f2ce57 ("net/smc: immediate freeing in smc_lgr_cleanup_early()") >Cc: stable@vger.kernel.org >Assisted-by: GPT-6.1-Sol >Signed-off-by: Chengfeng Ye >--- >Changes in v3: >- Serialize first registration with the teardown claim under the group list > lock, nesting conns_lock in the same order as connection reuse. >- Reject groups already being freed and clear conn->lgr on that path. >- Document the scheduling fix prerequisite in the permanent commit message. > >Changes in v2: >- Pin newly created link groups before publication, covering the > registration failure handoff to early cleanup. Drop the temporary hold > after cleanup on failure, or after the connection hold on success. >- Send after the free-work scheduling fix and reuse its standalone > freeing bool and locked early-cleanup transition. >- Pin the link group across the smc_conn_abort() early-cleanup ownership > check. > >v1: https://lore.kernel.org/r/20260927063607.3691520-1-nicoyip.dev@gmail.com/ > >v2: https://lore.kernel.org/r/20261003183237.2284245-3-nicoyip.dev@gmail.com/ > > net/smc/af_smc.c | 8 ++++++-- > net/smc/smc_core.c | 21 ++++++++++++++++++--- > 2 files changed, 24 insertions(+), 5 deletions(-) > >diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c >index e9f93b3ab435..97b0a0b51066 100644 >--- a/net/smc/af_smc.c >+++ b/net/smc/af_smc.c >@@ -1011,12 +1011,16 @@ static void smc_conn_abort(struct smc_sock *smc, int local_first) > struct smc_link_group *lgr = conn->lgr; > bool lgr_valid = false; > >- if (smc_conn_lgr_valid(conn)) >+ if (local_first && smc_conn_lgr_valid(conn)) { > lgr_valid = true; >+ smc_lgr_hold(lgr); >+ } > > smc_conn_free(conn); >- if (local_first && lgr_valid) >+ if (lgr_valid) { > smc_lgr_cleanup_early(lgr); >+ smc_lgr_put(lgr); >+ } > } > > /* check if there is a rdma device available for this connection. */ >diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c >index 660cd41ec720..c1bb284c4233 100644 >--- a/net/smc/smc_core.c >+++ b/net/smc/smc_core.c >@@ -693,6 +693,10 @@ void smc_lgr_cleanup_early(struct smc_link_group *lgr) > > smc_lgr_list_head(lgr, &lgr_lock); > spin_lock_bh(lgr_lock); >+ if (lgr->freeing) { >+ spin_unlock_bh(lgr_lock); >+ return; >+ } > /* do not use this link group for new connections */ > if (!list_empty(&lgr->list)) > list_del_init(&lgr->list); >@@ -999,6 +1003,7 @@ static int smc_lgr_create(struct smc_sock *smc, struct smc_init_info *ini) > lgr->buf_type = lgr->net->smc.sysctl_smcr_buf_type; > atomic_inc(&lgr_cnt); > } >+ smc_lgr_hold(lgr); /* lgr_put in smc_conn_create() */ > smc->conn.lgr = lgr; > spin_lock_bh(lgr_lock); > list_add_tail(&lgr->list, lgr_list); >@@ -2049,15 +2054,25 @@ int smc_conn_create(struct smc_sock *smc, struct smc_init_info *ini) > if (rc) > goto out; > lgr = conn->lgr; >- write_lock_bh(&lgr->conns_lock); >- rc = smc_lgr_register_conn(conn, true); >- write_unlock_bh(&lgr->conns_lock); >+ spin_lock_bh(lgr_lock); >+ if (lgr->freeing) { >+ conn->lgr = NULL; >+ rc = SMC_CLC_DECL_SYNCERR; This should not be SMC_CLC_DECL_SYNCERR, maybe SMC_CLC_DECL_INTERR or add a new error code. >+ } else { >+ write_lock_bh(&lgr->conns_lock); >+ rc = smc_lgr_register_conn(conn, true); >+ write_unlock_bh(&lgr->conns_lock); >+ } >+ spin_unlock_bh(lgr_lock); > if (rc) { > smc_lgr_cleanup_early(lgr); >+ smc_lgr_put(lgr); /* lgr_hold in smc_lgr_create() */ smc_lgr_put() may call smcr_buf_free() -> vfree(), which may sleep. And you put it in the spinlock. Best regards, Dust