From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=209.85.214.173 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793417248; b=YvPGDwoABvNlUHpKuu2kik8g3IWANuI7tqj63UsK7WkHOMl1MI2bpFBceaQg8NcpJvRg SjUkOv+NsIQGe+MWDWHj20oUlX6ScUGpYdtYfztWDf9UHgHFuwmXOqNHHleeos95oXeq1 F75VpEwI8VZV9Rr5pi6ozK3vqM8+NsBms3Ji2NgX/ujfcSiYvujdgobC3YA68fVdwQRdU 4b0Ct/E7LzxUpAsEJp5fv9egULV99+RjYCusD7OVkVcOTfbFntVgj6+fhrL6AVGU2NDRq rIr9E761AyQE479hZt/Rqur7LSIBKbBw3iOg3r5hFoMqaijVm0/ovKgj+TzWZe9N+ow== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793417248; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received:Received: From:To:Cc:Subject:Date:Message-Id:X-Mailer:In-Reply-To:References: MIME-Version:Content-Transfer-Encoding; bh=OLqqsp/okect8vN1Ll5uBxIlIn1JEHdL1FhjprUqk7k=; b=WmbMspGvZRefkkbVPvKZtUgZKhH+6mhQfx2w0xS8qnNkpDObLduuQTincfZeytRpnJaU xWeyNGFlW1bo98hXtiqcz4pLEU9zSosdwuulF7W4CtzS2VMe6XvPOKDVrGFroL9Eb6hdp kgnV/MgY2LlpxjwQt+oWIw+wnM01BCyaoteTC6HyiE9z7SnBAKS57+vbWb3Qlvo1fSAIa cXEiPMeBE8oAn3jTPdKfLM4Up2jvqj2F6V87iWySNescB7hG9++dm/dOmwOa3loRNBeJw bZeV7qOH/JcMtOHMGVTo8RD1I/Zq6GyStmlnhgYxyKMYQxDpZLHnK4yhpvs34DD2TaQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=0oWFuuCx; arc=none smtp.remote-ip=209.85.214.173 Received: from mail-pl1-f173.google.com (mail-pl1-f173.google.com [209.85.214.173]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9B043606A321 for ; Sat, 31 Oct 2026 03:27:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 9B043606A321 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=0oWFuuCx Received: by mail-pl1-f173.google.com with SMTP id d9443c01a7336-2e8fe8e343fso9399495ad.2 for ; Fri, 30 Oct 2026 20:27:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20260707; t=1793417247; x=1794022047; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=OLqqsp/okect8vN1Ll5uBxIlIn1JEHdL1FhjprUqk7k=; b=0oWFuuCxFJqXL0ZvsUyrJQxfxtOFvwyTRceUPq5jL0E0HoJJ/2VVo+7QZyyrYYZDpz KPh7DL6KBiUv7ILLQXcfwgevHLVesuppskmnxtXD5w2dI3CDVcux1UXtmk/Qk+jjK9mq zR8PrlRk7EMJaJDo59dxQfMVQWPWATCkro/hklgnGcWyqqNXqy2C1wTgd/ZLvDyhR3HB u8VIrR+S3WJsCYRmhjqWtahEHFMB7t+aCkO2/WRLmftaS9aMBUCLCFTqEzaynF/UXEHi CFYvTdHJZ4eDU2xdO0hyFVjJRwZ0/gRkRuYYbUmdSBeE5CbUJcplDiEAl+8VYM3t7813 nliQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1793417247; x=1794022047; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=OLqqsp/okect8vN1Ll5uBxIlIn1JEHdL1FhjprUqk7k=; b=WDS4Slf27ZstCw1CwngaluKPPUXR/glqHocEwSPTS5utQLdiDde1ul7CCU2Wg4bgIo UpGrcY2BmWvsT9knFIbl2HtZksLdQH135+F7JiQBJZomwq+XZS0lxGqDjRHvSqyHwtX5 VBX3Pkf/nY0JK9iKkUxcJFSWuqO/6vCo4GbX6QFCPcLJXLvI+ppszdG8rT0D1Fwz7tea pu/ylFmzP1kbRBDR1Xu+Gu8SW643n/kOkVfFLY6B8WSaRAuVKeV3V7+ezUL/iyKMZuDV sE5tTTvzwqCSVMPXnumWdwM5A1lVvJqCtLbqlgmS9Q0JiCzCVKLzAhZeaxZkOW5wLQLA QKEQ== X-Forwarded-Encrypted: i=1; AKwUvBwOJA8f6XrPjz7B5OxzZucodlSRfrWimMef+C1lE9BiwCBhD/v+s/gcrleC7NEF2LMj4V1dAJm2H+CSsQM=@vger.kernel.org X-Gm-Message-State: AFq9FYL5VuMTK1EVNyDZhPpnozrsxLUfP8sb59cPRuH1666nSiULZUM9 +iE6eN7xMBKm0mmgzCd4Hs9GzCemeRPSc0TCvFrNRvgHKoBEiJLWXukU X-Gm-Gg: AYBFou2JE+AOlyZQ+4GG9RDcZCn5ZU+uUvVc/dmuWYUwtVtZYuvP8dV3Fh+SHXOiR+T oP4UI9L6J9FXrj5qYtnpY/vaTEAFf25eOWXX76ER4u7cGenbrrEjBEb/y2k2nTMFO6hzTUOqAxw 7BlQ6UcabOhD9rcPklqDhg5OfVVdeTtvjlnTjcgNDRcdA81qSjrADzXXNMr+LPX5CDzPMMXZMKs MgiKYroqhhRYqtsf9xB2IMbTDY/bdvOVnhTYLObLBHdkIlylmLeluAxjnkU5YW6zZMwAafsJphV T7fAvIPKKIbAu2SK9tdALFS2UY8qXdHOghO1eXj25JxUpus2ldua7dJrnmGuKROcQQS2x75p+eK dqqLWy46ZKAxQxSwI0rUX5y9w7lF53A92KW/rfFtyqqnVNtZtTkdiT0VxBcIIpFQ4qKz7dsNrYJ SNmpnL0HX65v+JqEvprytF7ZVzY3Mt6cXIh5JQkDu6Us3TKUrr/ndRUv8NRPo0nabQIYhyn3+l6 h/wz+hCF/r5krJM3uLFnLxdh/tXhRuddL8RORoTJw1RRO7pwUjwbB3kL2mkU9YbPs5LEqy3aPT0 nb+Vl5VpSAr/hQgnY+hQZD0W X-Received: by 2002:a17:903:2442:b0:2e2:c90f:968c with SMTP id d9443c01a7336-2eb3646a99fmr39733865ad.44.1793417246841; Fri, 30 Oct 2026 20:27:26 -0700 (PDT) Received: from localhost ([111.228.63.84]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2eb39231422sm13203495ad.23.2026.10.30.20.27.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 30 Oct 2026 20:27:26 -0700 (PDT) From: Cen Zhang To: marcel@holtmann.org, luiz.dentz@gmail.com Cc: linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org, baijiaju1990@gmail.com, jjzuming@gmail.com, zzzccc427@gmail.com Subject: [PATCH v2 2/2] Bluetooth: SMP: Serialize root channel replacement Date: Sat, 31 Oct 2026 11:27:14 +0800 Message-Id: X-Mailer: git-send-email 2.34.1 In-Reply-To: References: X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit smp_register() replaces the SMP root channels when they are still registered from an earlier power-on. This happens when management powers on a controller that is already up with HCI_AUTO_OFF set: hci_power_on_sync() clears the flag and runs hci_powered_update_sync() again, which registers SMP so that the channels use the identity address chosen for this power-on. The WARN_ON() in smp_register() fires on this path, and the old channels and their SMP data are freed while two kinds of users can still hold them. HCI event handlers read hdev->smp_data under hdev->lock, for example smp_irk_matches() when resolving the target of a directed advertising report: HCI receive worker Power-on request hci_dev_lock(hdev) smp_irk_matches() chan = hdev->smp_data hci_powered_update_sync() smp_register() smp_del_chan(chan), chan freed reads chan->data SMP receive callbacks run on hdev->workqueue without hdev->lock and use the ECDH transform of the root, for example smp_cmd_public_key(): HCI receive worker (SMP) Power-on request smp_cmd_public_key() tfm = root's tfm_ecdh smp_register() smp_del_chan() crypto_free_kpp(tfm) compute_ecdh_secret(tfm, ...) Before commit 2ff13894cfb8 ("Bluetooth: Perform HCI update for power on synchronously") moved it to the request worker, registration ran from the completion callback of the power-on request in the HCI receive worker, which serialized it with both users. Run the registration on hdev->workqueue again and hold hdev->lock while it replaces the channels. smp_register() waits for the work and returns its result. Its callers hold the request lock but not hdev->lock, and no work on hdev->workqueue takes the request lock; hci_dev_close_sync() already drains this workqueue with the request lock held. Users that run under the request lock, such as smp_generate_rpa(), stay serialized by that lock. The reports below come from test kernels with scheduling hooks that widen these windows. The WARN_ON() in smp_register() was printed before each of them. KASAN report as below: ================================================================== BUG: KASAN: slab-use-after-free in smp_irk_matches+0x2fb/0x310 Read of size 8 at addr ffff88810c35f4a0 by task kworker/u17:0/520 Workqueue: hci0 hci_rx_work Call Trace: dump_stack_lvl+0x93/0xd0 print_report+0xce/0x630 kasan_report+0xe0/0x110 smp_irk_matches+0x2fb/0x310 process_adv_report.part.0+0x2ce/0x1680 hci_le_direct_adv_report_evt+0x2f8/0x4c0 hci_le_meta_evt+0x30c/0x5c0 hci_event_packet+0x4e8/0xc70 hci_rx_work+0x367/0xf00 process_one_work+0x908/0x19c0 worker_thread+0x65c/0xe40 kthread+0x34f/0x460 ret_from_fork+0x659/0x940 ret_from_fork_asm+0x1a/0x30 Allocated by task 522: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0xaa/0xb0 __kmalloc_cache_noprof+0x251/0x610 l2cap_chan_create+0x47/0x930 smp_add_cid+0x120/0x4f0 smp_register+0xa7/0x400 hci_powered_update_sync+0x88/0x720 hci_dev_open_sync+0xae0/0x2060 hci_set_powered_sync+0x2a9/0x720 set_powered_sync+0xaa/0x150 hci_cmd_sync_work+0x1b3/0x450 process_one_work+0x908/0x19c0 worker_thread+0x65c/0xe40 kthread+0x34f/0x460 ret_from_fork+0x659/0x940 ret_from_fork_asm+0x1a/0x30 Freed by task 522: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x5f/0x80 kfree+0x307/0x580 l2cap_chan_put+0x273/0x3a0 smp_del_chan+0x9f/0x170 smp_register+0x2e8/0x400 hci_powered_update_sync+0x88/0x720 hci_set_powered_sync+0x5e5/0x720 set_powered_sync+0xaa/0x150 hci_cmd_sync_work+0x1b3/0x450 process_one_work+0x908/0x19c0 worker_thread+0x65c/0xe40 kthread+0x34f/0x460 ret_from_fork+0x659/0x940 ret_from_fork_asm+0x1a/0x30 The buggy address belongs to the object at ffff88810c35f000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 1184 bytes inside of freed 2048-byte region [ffff88810c35f000, ffff88810c35f800) ================================================================== KASAN report as below: ================================================================== BUG: KASAN: slab-use-after-free in compute_ecdh_secret+0x856/0xa50 Read of size 4 at addr ffff8881071f4f00 by task kworker/u17:2/500 Workqueue: hci1 hci_rx_work Call Trace: dump_stack_lvl+0x93/0xd0 print_report+0xce/0x630 kasan_report+0xe0/0x110 compute_ecdh_secret+0x856/0xa50 smp_recv_cb+0x3acf/0x93b0 l2cap_recv_frame+0x13cc/0x8830 l2cap_recv_acldata+0xe9f/0x10e0 hci_rx_work+0x5a6/0xf00 process_one_work+0x908/0x19c0 worker_thread+0x65c/0xe40 kthread+0x34f/0x460 ret_from_fork+0x659/0x940 ret_from_fork_asm+0x1a/0x30 Allocated by task 497: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0xaa/0xb0 __kmalloc_node_noprof+0x2f2/0x7b0 crypto_create_tfm_node+0x92/0x390 crypto_alloc_tfm_node+0xf5/0x220 smp_add_cid+0xc1/0x4f0 smp_register+0x9d/0x430 hci_powered_update_sync+0x82/0x680 hci_set_powered_sync+0x4f4/0x750 set_powered_sync+0xb8/0x210 hci_cmd_sync_work+0x1b3/0x450 process_one_work+0x908/0x19c0 worker_thread+0x65c/0xe40 kthread+0x34f/0x460 ret_from_fork+0x659/0x940 ret_from_fork_asm+0x1a/0x30 Freed by task 497: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x5f/0x80 kfree+0x307/0x580 crypto_destroy_tfm+0xdd/0x230 smp_del_chan+0x8b/0x180 smp_register+0x29d/0x430 hci_powered_update_sync+0x82/0x680 hci_set_powered_sync+0x4f4/0x750 set_powered_sync+0xb8/0x210 hci_cmd_sync_work+0x1b3/0x450 process_one_work+0x908/0x19c0 worker_thread+0x65c/0xe40 kthread+0x34f/0x460 ret_from_fork+0x659/0x940 ret_from_fork_asm+0x1a/0x30 The buggy address belongs to the object at ffff8881071f4f00 which belongs to the cache kmalloc-128 of size 128 The buggy address is located 0 bytes inside of freed 128-byte region [ffff8881071f4f00, ffff8881071f4f80) ================================================================== Fixes: 2ff13894cfb8 ("Bluetooth: Perform HCI update for power on synchronously") Signed-off-by: Cen Zhang --- Assisted-by: LLM net/bluetooth/smp.c | 36 +++++++++++++++++++++++++++++++++++- 1 file changed, 35 insertions(+), 1 deletion(-) diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c index 0e442cc2a35da..552b6b3713c3a 100644 --- a/net/bluetooth/smp.c +++ b/net/bluetooth/smp.c @@ -3369,7 +3369,8 @@ int smp_force_bredr(struct hci_dev *hdev, bool enable) return 0; } -int smp_register(struct hci_dev *hdev) +static int __smp_register(struct hci_dev *hdev) + __must_hold(&hdev->lock) { struct l2cap_chan *chan; @@ -3419,6 +3420,39 @@ int smp_register(struct hci_dev *hdev) return 0; } +struct smp_register_work { + struct work_struct work; + struct hci_dev *hdev; + int err; +}; + +static void smp_register_func(struct work_struct *work) +{ + struct smp_register_work *reg = + container_of(work, struct smp_register_work, work); + struct hci_dev *hdev = reg->hdev; + + hci_dev_lock(hdev); + reg->err = __smp_register(hdev); + hci_dev_unlock(hdev); +} + +int smp_register(struct hci_dev *hdev) +{ + struct smp_register_work reg = { .hdev = hdev }; + + /* HCI event handlers use the root channels under hdev->lock, and + * SMP receive callbacks use them from hdev->workqueue. Replace the + * channels from that workqueue while holding hdev->lock. + */ + INIT_WORK_ONSTACK(®.work, smp_register_func); + queue_work(hdev->workqueue, ®.work); + flush_work(®.work); + destroy_work_on_stack(®.work); + + return reg.err; +} + void smp_unregister(struct hci_dev *hdev) { struct l2cap_chan *chan;