From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from stravinsky.debian.org (stravinsky.debian.org [82.195.75.108]) (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 91D4B3F54DD; Wed, 19 Aug 2026 11:45:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=82.195.75.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787139952; cv=none; b=gByWzwBKqbC3+rwLKc1o7PeEeRaDbKCS4UFa2eSxtt8ZxtKYqBRMQZjbF85fz9f2/fTcQ4HsB0TmmufpiLn269tQkWSK9lhSqN6vPwWAtw2iALRRTtc/IPoRsPA8sQqWENaIv3XrbNt9Z16UMFLiOyRILUBkZiYx6B4scLunn3g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787139952; c=relaxed/simple; bh=sYs6Sg8z01QB2GLvk6s1IsC5i9DXzY/sN5SmRfsk5+k=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=k5r0CPgjIg20/5SIiuFmCWLcaFDR7nwjr+Gbw03XPTOlL2appxyv15MQz8o8HCnceSOht7gCnOrzdBVhnDlt0jdJjko3TYSwSFaP1BY8G2+QHJapfk9RKxJ04VrB085qH5gSkh22KOwtTL3qw1G7HNaTILi2sosj0m0YkQQq/QY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org; spf=pass smtp.mailfrom=debian.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b=HXS1k7ZS; arc=none smtp.client-ip=82.195.75.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=debian.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b="HXS1k7ZS" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=debian.org; s=smtpauto.stravinsky; h=X-Debian-User:In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=hLfRj57yEBsc06jH6wJGVAOT1OrEjp5Uv/NlEfdHEFo=; b=HXS1k7ZSluuCyn35A5gwjfUD/w 9F/0n8m6v/PowEwOmU0kT6F9mthptoEdQAt61/C/XKOaUTOCoDmVUqrLqRV2Lao6z5GU2Qj3qnRWM Y4tQXz9sYqTtsvMCEq7WTwbqrNWfBg8608si2oZKm0vKXJUozo0waSslYl7lBq4S0R54l/ZvtwrX7 Q1aiArQ1aNa0xggKtzponuNJ8V8XOVDMCW1BJoQ9N9fVWqwKzwUlrcmED0u6+e1It4E26jyfsD9LO 4YH0E/05mC01I+QkBKW74NBMbLKhmtC10pjkrogLxN94myoWtSLS6sXpuM79n/IJQMTpuW9Nl1MAf q+T1naDg==; Received: from authenticated-user by stravinsky.debian.org with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.96) (envelope-from ) id 1wwejd-009ldD-1x; Wed, 19 Aug 2026 11:45:34 +0000 Date: Wed, 19 Aug 2026 04:45:26 -0700 From: Breno Leitao To: Yehyeong Lee Cc: alibuda@linux.alibaba.com, dust.li@linux.alibaba.com, sidraya@linux.ibm.com, wenjia@linux.ibm.com, kuba@kernel.org, davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, 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 Subject: Re: [PATCH net v7 1/3] net/smc: fix use-after-free of the LLC qentry in smc_llc_srv_add_link() Message-ID: References: <20260819023306.644849-1-yhlee@isslab.korea.ac.kr> <20260819023306.644849-2-yhlee@isslab.korea.ac.kr> Precedence: bulk X-Mailing-List: netdev@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: <20260819023306.644849-2-yhlee@isslab.korea.ac.kr> X-Debian-User: leitao On Wed, Aug 19, 2026 at 11:33:04AM +0900, 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 > Reviewed-by: Sidraya Jayagond > Signed-off-by: Yehyeong Lee Reviewed-by: Breno Leitao