From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 29C82C5AC7A for ; Fri, 7 Aug 2026 09:27:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4A7E06B007B; Fri, 7 Aug 2026 05:27:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 47F536B008A; Fri, 7 Aug 2026 05:27:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 348466B0092; Fri, 7 Aug 2026 05:27:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 0D04A6B007B for ; Fri, 7 Aug 2026 05:27:35 -0400 (EDT) Received: from smtpin07.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 949ACA1A8F for ; Fri, 7 Aug 2026 09:27:34 +0000 (UTC) X-FDA: 85073945628.07.EF1AB98 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf19.hostedemail.com (Postfix) with ESMTP id E24BF1A0006 for ; Fri, 7 Aug 2026 09:27:32 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=A9fzMAj9; spf=pass (imf19.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1786094852; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=7bLwVOoBAN+V0pmI0BJbccWYshh97vq0Mu/2qyzbG+w=; b=ykCMt3N5oLH3a1owCgpZ0uTSAUi/cgCj7I3FJqws/ceZrtrUTbCOLcrGY/V90u+bNH/BHA 2Y8mIKn9xd2VQtcBQS79bbffhyAXqvIK1jy9zC3iC5pW/c974J6OHn6Kx8mw25d4s14u63 tRp7atyCnr9vokggszx0MViv1tjPvJQ= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1786094852; b=XKOINr+Z03kNSgD4/cvliRSJuH4m5iC4eF5gKO4hlGoZXyk5ewvd4SBfM66R1zLN/Of/2m VuqLSIDtmaGfAJtYNrqW4BsBz7PJ0QuAupBl7VXYz+c36Iww0QwN5zorA/eQIIHvhAepFN Jf6/A1AVnpfThnJP+FpGAXP4I2K/XEo= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=A9fzMAj9; spf=pass (imf19.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 3175160A86; Fri, 7 Aug 2026 09:27:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B730B1F000E9; Fri, 7 Aug 2026 09:27:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786094851; bh=7bLwVOoBAN+V0pmI0BJbccWYshh97vq0Mu/2qyzbG+w=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=A9fzMAj9ZqlgXqw49U/BCd3XPdYf8bRmHb0iQkAJmlBPsGKE2n0LNoj8ahftUza9e 4vHcv5Anvq0w8fv0J0C7XBSTHGgK0A5+4sOxLqIktAi7N8stQMHo3OrsWki+1Bhrgx rEEoRehj2rh3kGj7oMjfCUYz9aJA9fuPue/m1jRjx3gI3Wlhogmp8aEXdPrm9gl3pe 6aGKZzqAjiEmZ05X9c+Rv8pbgvCvtOpEi9ddp6q3T+uodw11AQyrv2922d8JVFv5kY VAerHya88TvofPgvQCntSWPK6QNdUxZJHQFtsMmxDakis+usg+7MfYgyanFtzEWanE 1FV/Ppgf0NU5Q== Message-ID: Date: Fri, 7 Aug 2026 11:27:24 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] fork: reset pointer tag of vmapped thread stack before vfree To: sparkhuang , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Andrew Morton , Kees Cook Cc: Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , K Prateek Nayak , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Andrey Ryabinin , linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org References: <20260806123020.90869-1-huangshaobo3@xiaomi.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20260806123020.90869-1-huangshaobo3@xiaomi.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam07 X-Rspam-User: X-Stat-Signature: 9sg8ynqehgemtzno64t4118njn5crfss X-Rspamd-Queue-Id: E24BF1A0006 X-HE-Tag: 1786094852-999516 X-HE-Meta: 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 yBugpo+Z Q3mK07+sxWNmcG7dZM6qs3Q9jFH3AFbCxepzpusIFuIBlpmnH2D5C3+dAzklDM+RIViF0GrouwsLPOnKbyhSMZXiyVlmZAMgVzrZz+PtiTOMVeYl680VPh/PqD45c/C73o2fdtzP9pJJ/YXkRgsrEgBVtyV9jC1bBqwgs8oDc1FOGVYhT7ZPMy+QH0ydiDTq0DrJJL7+jcY5y+TH72rH0rQVLkTU54sAnsAdczRrnjQ3KcaiU4OuLLOWI4jBUe8okFfJxAloLZtKdmUJpK0xCFpJN8CRH2tHZ7DeBf9g0ldf9k37+xwjVOUaNEzlHSceOTuP9A+RO1qdoB5c2jLLA2R4FnrCj4X7rzBW+Cv4IZKNkI7o= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/6/26 14:30, sparkhuang wrote: > When a thread stack is freed via RCU callback, > thread_stack_free_rcu() calls vfree(vm_area->addr). In RCU callback > context (e.g. from rcu_nocb_cb_kthread with BH disabled, or from > RCU_SOFTIRQ), in_interrupt() returns true, so vfree() routes to > vfree_atomic(). > > vfree_atomic() uses the freed memory as llist storage by calling > llist_add((struct llist_node *)addr, &p->list), which writes 8 bytes > to the address being freed. With KASAN SW_TAGS enabled, > vm_area->addr carries a random tag assigned during allocation by > kasan_unpoison_vmalloc(). If the shadow memory covering this region > has been set to KASAN_TAG_KERNEL (0xFF) — e.g. by > kasan_unpoison_task_stack() using task->stack, which was already > reset to 0xFF by kasan_reset_tag() at allocation time — the shadow > byte (0xFF) no longer matches the pointer tag on vm_area->addr, > and the write in llist_add triggers a KASAN invalid-access report: > > ================================================================== > BUG: KASAN: invalid-access in vfree_atomic+0x90/0x150 > Write of size 8 at addr c2ffffc0a8f70000 by task rcuop/7/75 > Pointer tag: [c2], memory tag: [ff] > > CPU: 5 UID: 0 PID: 75 Comm: rcuop/7 Tainted: G S W OE > Hardware name: XiaoMi Xring_o1 UDP PHONE (DT) > Call trace: > show_stack+0x18/0x28 > __dump_stack+0x28/0x3c > dump_stack_lvl+0xac/0xf0 > print_address_description+0x7c/0x25c > print_report+0x70/0x8c > kasan_report+0xdc/0x13c > __hwasan_store8_noabort+0xe8/0xf8 > vfree_atomic+0x90/0x150 > vfree+0x220/0x298 > thread_stack_free_rcu+0x3c/0x4c > rcu_do_batch+0x308/0xaf0 > rcu_nocb_cb_kthread+0x33c/0x708 > kthread+0x364/0x3cc > ret_from_fork+0x10/0x20 > > The buggy address belongs to a 8-page vmalloc region starting at > 0xc2ffffc0a8f70000 allocated at copy_process+0x1ac/0x12e4 > > Memory state around the buggy address: > ffffffc0a8f6ff00: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe > >ffffffc0a8f70000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > ^ > ffffffc0a8f70100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > ================================================================== Were you able to reproduce this more than once? Does this relate to CONFIG_KASAN_STACK? Can you share the kernel config? -- Cheers, David