From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 6B162415B8F; Fri, 4 Sep 2026 05:33:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788500028; cv=none; b=Z+raP7qLmtBeRft3lav8HjqE/QLO1V1lYSVb2AAk9gQOflB06jGYqkeZQg8n3y58Fouqe/EKFBcAGvEvmAKKj5UvRQc84+odTubUsVY+LvR6BPBr920Z75Ay4PE8yOhy3nXUoEQ9S6hC9P4t/1jk8qS79sf7J2PllUAljzwmcyI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788500028; c=relaxed/simple; bh=uTB5shcy6G2tLlrzA47qT23vAKpOsI2uFaNIW0p8eMQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=iHMOu+DuVE1ZqQp43YJYaIkofTPnhgVyu8froqgXXex9kp8tsU/fNL8HE5oZp9YbfXyN4EkaktC9wL38oKNvwEFToZ7akVf20TQ06RtxtmCNPkxYfyX6Zq1S6qtNUqSAaD+lEhuhPRdCv9/a6IlaAK9d/ywjHGroPXVDA5YXgsw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=eqGOyxls; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="eqGOyxls" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8F3441F00A3D; Fri, 4 Sep 2026 05:33:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788500027; bh=GwMV5FUf1H+ERDVu5m1CkGsED3n8Rp5yxHzkFak38uQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=eqGOyxlsJ/BC8P7sfHvFAaIenS7Wixd4H5AgN7nRqvcUk3i8o3fbyn7lhoDnmKPKy 0s9O2S+sJkT/Uf9pFWoEd1HDNV97f0RNH6zPXs7N/498w3tG3XZJQl3R2gRdoGJY/E wYRDvpB2ESdtYCrOpel2V/t+HYHR0ENSERQ+Dp6k= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sidraya Jayagond , Yehyeong Lee , Breno Leitao , Jakub Kicinski Subject: [PATCH 7.2 624/713] net/smc: fix use-after-free of the LLC qentry in smc_llc_srv_add_link() Date: Fri, 4 Sep 2026 06:59:52 +0200 Message-ID: <20260904045817.813579328@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260904045803.810145556@linuxfoundation.org> References: <20260904045803.810145556@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yehyeong Lee commit a42a459ef0e54cb0c4b3e43e21cb0e658e664f64 upstream. 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 Link: https://patch.msgid.link/20260819023306.644849-2-yhlee@isslab.korea.ac.kr Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/smc/smc_llc.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) --- a/net/smc/smc_llc.c +++ b/net/smc/smc_llc.c @@ -1505,7 +1505,7 @@ int smc_llc_srv_add_link(struct smc_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; } @@ -1516,7 +1516,8 @@ int smc_llc_srv_add_link(struct smc_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) @@ -1534,14 +1535,14 @@ int smc_llc_srv_add_link(struct smc_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);