From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (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 B18F93812FB; Tue, 18 Aug 2026 15:29:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.156.1 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787066988; cv=none; b=Pi1BfuvwmQrT086Bna4zgzKV6YAo0byXQqg1vUXmcx+RygmDyxL0dJb7FTQ0WnH8QI6JEmQudnfLUgp1/uw7CN327adei41NqdEnn4uvAVSl/AonAW6DTG+aPyk/ZZUogVY7wuvVerapepENEQeMbneI5Mfd/pqrGovRbWAU3YE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787066988; c=relaxed/simple; bh=xl0NyXNqSvTP56iARQ/D0BKi55b3jNZbbiRk3wgwyk4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=BKThDcoYQ6ykC9Z8JrPGTswL7HlFW8uJezM1OQhnrR0zE0JTbdyq3RkRXfLP3RgqJEKtsaDujDCPUrS25pO2BtylsK5j/JX4SzMN8VyXvz2AiF/a9veprPXHKYxzoReOIX1TcURSMtpxO8MOQCPixc/+EdFfVbiYSYBt4aQVLM0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; spf=pass smtp.mailfrom=linux.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=r2mx6SYv; arc=none smtp.client-ip=148.163.156.1 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="r2mx6SYv" Received: from pps.filterd (m0360083.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 67IE3Zkv455087; Tue, 18 Aug 2026 15:29:27 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=pp1; bh=adT1B1 9TjTjVHbV+6tXcTgDOYZLt+4FWuGuxN8YIy5A=; b=r2mx6SYvk/hRQgqgF92eqK xBp2gu5DgZEDNsQ/ZwLz0Bi6Bt+UX3lj7om03tGtGZ51q7CWF32WB6G6RLRJgxPC DP9HUEABov6vgQ5xcD9YnbarfUOWq+4jP37njU4fok6p2T+8H8BzbiSOwNcp7VBf UDmyk20lE7JRPfXIoMeu3pm0MRlxRU2Vxa00hK338c2mPHS2U0XBaZXEHx5SXyOR 4RRlv3o9rrnxpid9T1N6e84DDtX0gtXCeV9NaL8XkSM4wOJ6JSnqPHLKpn/EaYGg FvWIsAT3OenmP9j0ANjTqCRDbpnrQNL2jtEQ0u0lYwF4IM9l1q5K0oXG/4UADAww == Received: from ppma23.wdc07v.mail.ibm.com (5d.69.3da9.ip4.static.sl-reverse.com [169.61.105.93]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4g2fm3s4p3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 18 Aug 2026 15:29:26 +0000 (GMT) Received: from pps.filterd (ppma23.wdc07v.mail.ibm.com [127.0.0.1]) by ppma23.wdc07v.mail.ibm.com (8.18.1.7/8.18.1.7) with ESMTP id 67IFQOQS020197; Tue, 18 Aug 2026 15:29:25 GMT Received: from smtprelay05.fra02v.mail.ibm.com ([9.218.2.225]) by ppma23.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4g33xh3w3t-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 18 Aug 2026 15:29:25 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (smtpav02.fra02v.mail.ibm.com [10.20.54.101]) by smtprelay05.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 67IFTLcp47251746 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 18 Aug 2026 15:29:21 GMT Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1B5B520043; Tue, 18 Aug 2026 15:29:21 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 19E1E20040; Tue, 18 Aug 2026 15:29:16 +0000 (GMT) Received: from [9.39.17.238] (unknown [9.39.17.238]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 18 Aug 2026 15:29:15 +0000 (GMT) Message-ID: Date: Tue, 18 Aug 2026 20:59:15 +0530 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 v6 1/3] net/smc: fix use-after-free of the LLC qentry in smc_llc_srv_add_link() To: Yehyeong Lee , alibuda@linux.alibaba.com, dust.li@linux.alibaba.com, wenjia@linux.ibm.com, kuba@kernel.org, davem@davemloft.net, edumazet@google.com, pabeni@redhat.com Cc: leitao@debian.org, horms@kernel.org, mjambigi@linux.ibm.com, tonylu@linux.alibaba.com, guwen@linux.alibaba.com, guangguan.wang@linux.alibaba.com, kees@kernel.org, gustavoars@kernel.org, netdev@vger.kernel.org, linux-rdma@vger.kernel.org, linux-s390@vger.kernel.org, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20260811231902.47089-1-yhlee@isslab.korea.ac.kr> <20260811231902.47089-2-yhlee@isslab.korea.ac.kr> Content-Language: en-US From: Sidraya Jayagond In-Reply-To: <20260811231902.47089-2-yhlee@isslab.korea.ac.kr> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-GUID: HVmFH0Dq7NDAPlFAaSHP9FCOrXOpKxgN X-Proofpoint-ORIG-GUID: iIWA3Bmrpev1fNI1VUGPY8WetMFYBMO1 X-Proofpoint-Spam-Info: AW1haW4tMjYwODE4MDExMCBTYWx0ZWRfX4qAOgw9+5jU9 B3xw7ykniW16ac/ej184Avrde6C7kxU1uq3eMWtOhd7ja5KrnUvVDtGLz3WGNiT5xg0D6igDwWN pFDenC1eOyT7rgnbI6Tq/CHuzJpSRs4= X-Authority-Analysis: v=2.4 cv=WtQb99fv c=1 sm=1 tr=0 ts=6a847a57 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=kukDy1qahNa2q44RZiwA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODE4MDExMCBTYWx0ZWRfX24F9QwQRwMHe nF1W2GkS2bhBeHMk+Zjou8o3I3G5L7zB13ZCqVYO80Kk5r+7qsWQQkkKEPy0z2Ae6cXIXzUHz1I 6newb0Vi8XwJUuTdJtTdZk3tirIkmKJxvDVkeBfBYjuEtaqajPii8O5vebVI70NfFTMfkGXzEaj NZczenBB3dvww2jSs8wvhLP03foGpiVRNRo0O6ZSDMNvDvYFp5dnWaeqe0Nl1t6ij1fRq1udbxy YX45hx7wd6SMeIOtdFo+0WWqYyX1Y+LySNzqSXQQnJKiYsrAD9BSU5Ie9qJdlft9POzdPQkkwOC 4QH2dQ19XiTOsLc1aL1O2C60hydpmWrKLIqBh3SsN52mpcZ2YtH4lSVNrAsQPV4t4Yx8Tq7BJ8b psfV/i+nfTZHP33arVHw6bdvEQEtjQgweSkrH3ngnZ6X1DEpF/VLFVjDCiNd/7iByeqHD02gavv sN0OBHlm8N67W1SMRLA== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-18_02,2026-08-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 spamscore=0 malwarescore=0 suspectscore=0 phishscore=0 lowpriorityscore=0 clxscore=1011 adultscore=0 priorityscore=1501 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608180110 On 12/08/26 4:49 am, Yehyeong Lee wrote: > smc_llc_srv_add_link() keeps add_llc pointing into the queue entry: > > add_llc = &qentry->msg.add_link; smc_llc.c:1482 > ... > smc_llc_save_add_link_info(link_new, add_llc); smc_llc.c:1494 > smc_llc_flow_qentry_del(&lgr->llc_flow_lcl); smc_llc.c:1495 > ... > u8 *llc_msg = smc_link_shared_v2_rxbuf(link) ? > (u8 *)lgr->wr_rx_buf_v2 : (u8 *)add_llc; smc_llc.c:1504 > smc_llc_save_add_link_rkeys(link, link_new, llc_msg); smc_llc.c:1506 > > smc_llc_flow_qentry_del() kfree()s the entry, so on a link without a shared > v2 receive buffer the pointer handed to smc_llc_save_add_link_rkeys() is > already freed. Before the Fixes: commit that branch always used > lgr->wr_rx_buf_v2 and add_llc was not used after the free. > > Reproduced on an unpatched tree over rxe, with KASAN, kasan_multi_shot > and a link forced to max_recv_sge == 1: the entry is freed and read by > the same call, and the freeing frame is smc_llc_srv_add_link() itself. > > [ 2.523161] BUG: KASAN: slab-use-after-free in smc_llc_save_add_link_rkeys+0x333/0x350 > [ 2.523499] Read of size 2 at addr ffff8880052194de by task kworker/0:1/11 > [ 2.523789] > [ 2.523862] CPU: 0 UID: 0 PID: 11 Comm: kworker/0:1 Not tainted 7.2.0-rc5-p0-g2c9dd296545d #35 PREEMPT(lazy) > [ 2.523865] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 > [ 2.523866] Workqueue: smc_hs_wq smc_listen_work > [ 2.523869] Call Trace: > [ 2.523870] > [ 2.523871] dump_stack_lvl+0x53/0x70 > [ 2.523872] print_report+0xd0/0x630 > [ 2.523874] ? __pfx__raw_spin_lock_irqsave+0x10/0x10 > [ 2.523876] ? smc_llc_save_add_link_rkeys+0x333/0x350 > [ 2.523878] kasan_report+0xce/0x100 > [ 2.523879] ? smc_llc_save_add_link_rkeys+0x333/0x350 > [ 2.523881] smc_llc_save_add_link_rkeys+0x333/0x350 > [ 2.523883] ? smcr_buf_reg_lgr+0x2a4/0x660 > [ 2.523885] smc_llc_srv_add_link+0xaa2/0x1e50 > [ 2.523888] ? _printk+0xba/0xf0 > [ 2.523897] ? __pfx_smc_llc_srv_add_link+0x10/0x10 > [ 2.523899] ? down_write+0xb0/0x130 > [ 2.523903] ? __pfx_down_write+0x10/0x10 > [ 2.523905] smc_listen_work+0x489e/0x4d00 > [ 2.523907] ? kmem_cache_free+0x1c6/0x3a0 > [ 2.523911] ? __pfx_smc_listen_work+0x10/0x10 > [ 2.523913] ? release_sock+0x148/0x1d0 > [ 2.523915] ? smc_tcp_listen_work+0xb4f/0xfc0 > [ 2.523917] ? _raw_spin_lock_irq+0x80/0xe0 > [ 2.523918] ? __pfx__raw_spin_lock_irq+0x10/0x10 > [ 2.523920] process_one_work+0x633/0x1030 > [ 2.523922] ? assign_work+0x11d/0x370 > [ 2.523924] worker_thread+0x45b/0xd10 > [ 2.523926] ? __pfx_worker_thread+0x10/0x10 > [ 2.523928] ? __pfx_worker_thread+0x10/0x10 > [ 2.523929] kthread+0x2c6/0x3b0 > [ 2.523931] ? recalc_sigpending+0x15c/0x1e0 > [ 2.523934] ? __pfx_kthread+0x10/0x10 > [ 2.523935] ret_from_fork+0x36e/0x5a0 > [ 2.523937] ? __pfx_ret_from_fork+0x10/0x10 > [ 2.523938] ? __switch_to+0x572/0xdd0 > [ 2.523943] ? __pfx_kthread+0x10/0x10 > [ 2.523944] ret_from_fork_asm+0x1a/0x30 > [ 2.523947] > [ 2.523948] > [ 2.531253] Allocated by task 48: > [ 2.531399] kasan_save_stack+0x33/0x60 > [ 2.531570] kasan_save_track+0x14/0x30 > [ 2.531737] __kasan_kmalloc+0x8f/0xa0 > [ 2.531905] __kmalloc_cache_noprof+0x158/0x370 > [ 2.532100] smc_llc_enqueue+0x72/0x560 > [ 2.532268] smc_wr_rx_tasklet_fn+0x474/0xa80 > [ 2.532491] tasklet_action_common+0x20f/0x8a0 > [ 2.532714] handle_softirqs+0x18e/0x590 > [ 2.532886] do_softirq+0x3b/0x60 > [ 2.533036] __local_bh_enable_ip+0x61/0x70 > [ 2.533221] __alloc_skb+0x732/0x890 > [ 2.533384] rxe_init_packet+0x16b/0x4f0 > [ 2.533567] prepare_ack_packet+0xb8/0x830 > [ 2.533760] rxe_receiver+0x495/0x96e0 > [ 2.533933] do_work+0x144/0x470 > [ 2.534078] process_one_work+0x633/0x1030 > [ 2.534257] worker_thread+0x45b/0xd10 > [ 2.534424] kthread+0x2c6/0x3b0 > [ 2.534569] ret_from_fork+0x36e/0x5a0 > [ 2.534737] ret_from_fork_asm+0x1a/0x30 > [ 2.534907] > [ 2.534980] Freed by task 11: > [ 2.535112] kasan_save_stack+0x33/0x60 > [ 2.535279] kasan_save_track+0x14/0x30 > [ 2.535444] kasan_save_free_info+0x3b/0x60 > [ 2.535625] __kasan_slab_free+0x43/0x70 > [ 2.535798] kfree+0x121/0x380 > [ 2.535935] smc_llc_srv_add_link+0x9a8/0x1e50 > [ 2.536128] smc_listen_work+0x489e/0x4d00 > [ 2.536305] process_one_work+0x633/0x1030 > [ 2.536482] worker_thread+0x45b/0xd10 > [ 2.536652] kthread+0x2c6/0x3b0 > [ 2.536794] ret_from_fork+0x36e/0x5a0 > [ 2.536958] ret_from_fork_asm+0x1a/0x30 > [ 2.537133] > [ 2.537205] The buggy address belongs to the object at ffff888005219480 > [ 2.537205] which belongs to the cache kmalloc-96 of size 96 > [ 2.537719] The buggy address is located 94 bytes inside of > [ 2.537719] freed 96-byte region [ffff888005219480, ffff8880052194e0) > [ 2.538216] > [ 2.538289] The buggy address belongs to the physical page: > [ 2.538524] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5219 > [ 2.538857] flags: 0x100000000000000(node=0|zone=1) > [ 2.539066] page_type: f5(slab) > [ 2.539210] raw: 0100000000000000 ffff888001041280 dead000000000122 0000000000000000 > [ 2.539534] raw: 0000000000000000 0000000000200020 00000000f5000000 0000000000000000 > [ 2.539863] page dumped because: kasan: bad access detected > [ 2.540098] > [ 2.540170] Memory state around the buggy address: > [ 2.540379] ffff888005219380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > [ 2.540684] ffff888005219400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > [ 2.540988] >ffff888005219480: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc > [ 2.541291] ^ > [ 2.541548] ffff888005219500: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc > [ 2.541857] ffff888005219580: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc > > The offset is past the 72-byte queue entry because the out-of-bounds read > fixed by the next patch is on the same line; what this patch removes is the > free at smc_llc_srv_add_link+0x9a8 happening before the read at +0xaa2. > > Detach the entry instead of freeing it there, and free it at the single > exit label. The reject path has to detach as well, otherwise it would be > freed twice. > > This changes only the lifetime of the entry. The same read still runs past > its end until the next two patches bound it, so a backport wants all three. > > Fixes: 27ef6a9981fe ("net/smc: support SMC-R V2 for rdma devices with max_recv_sge equals to 1") > Cc: stable@vger.kernel.org > Signed-off-by: Yehyeong Lee > --- > Changes since v5: return through the existing exit label. > > net/smc/smc_llc.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/net/smc/smc_llc.c b/net/smc/smc_llc.c > index 954b2ff1815c..055a03eee5b5 100644 > --- a/net/smc/smc_llc.c > +++ b/net/smc/smc_llc.c > @@ -1481,7 +1481,7 @@ int smc_llc_srv_add_link(struct smc_link *link, > } > add_llc = &qentry->msg.add_link; > if (add_llc->hd.flags & SMC_LLC_FLAG_ADD_LNK_REJ) { > - smc_llc_flow_qentry_del(&lgr->llc_flow_lcl); > + smc_llc_flow_qentry_clr(&lgr->llc_flow_lcl); > rc = -ENOLINK; > goto out_err; > } > @@ -1492,7 +1492,8 @@ int smc_llc_srv_add_link(struct smc_link *link, > lgr_new_t = SMC_LGR_ASYMMETRIC_PEER; > } > smc_llc_save_add_link_info(link_new, add_llc); > - smc_llc_flow_qentry_del(&lgr->llc_flow_lcl); > + /* add_llc still points into qentry, so only detach it here */ > + smc_llc_flow_qentry_clr(&lgr->llc_flow_lcl); > > rc = smc_ib_ready_link(link_new); > if (rc) > @@ -1512,14 +1513,14 @@ int smc_llc_srv_add_link(struct smc_link *link, > rc = smc_llc_srv_conf_link(link, link_new, lgr_new_t); > if (rc) > goto out_err; > - kfree(ini); > - return 0; > + goto out; > out_err: > if (link_new) { > link_new->state = SMC_LNK_INACTIVE; > smcr_link_clear(link_new, false); > } > out: > + kfree(qentry); > kfree(ini); > if (send_req_add_link_resp) > smc_llc_send_req_add_link_response(req_qentry); Reviewed-by: Sidraya Jayagond