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Thu, 29 Oct 2026 10:46:06 +0000 (UTC) X-FDA: 85375333932.21.EBC75FD Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf03.hostedemail.com (Postfix) with ESMTP id 6439F20006 for ; Thu, 29 Oct 2026 10:46:04 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=OQBViomQ; spf=pass (imf03.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 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=1793270764; 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=RWtxWJ8Mj0Rtl84/opbh6HrMgPdbznSuYDREGzIgtS8=; b=YOmU+Fmj+UyhQERFbZEcYLbp60KscUy223iuPclQqnYmbE3rrysIAYkBVXRJm/O8iBVXaZ VXc/8EKC5Zozw7bA77zp6vOn5e6/n/MCrwCQzBEhAS5DRYD+HRCChZSNi8XPEzS8gLVNHI mfMeVt1ERuho7xCCdtRCZ7UZMazzw9w= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793270764; b=oivlvzDfZ9QgThHq7PiPqmZd4Hlg3xHQQHGQuh/jGyaQFKWm9jT7WAOeXl4w7KAe9bOMHD GqXJ067frGnw8yZHbFHlRpEOg6boviR7ulZRe/MP+IFu62UQCjUvRCKyJ6ybtjGBHTQSfd CbKHCg1xyoe3Q7jkiKvdcCn9lBRdZ8E= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=OQBViomQ; spf=pass (imf03.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 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 sea.source.kernel.org (Postfix) with ESMTP id A9F3E43EBA; Thu, 29 Oct 2026 10:46:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A31C1F01828; Thu, 29 Oct 2026 10:46:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793270763; bh=RWtxWJ8Mj0Rtl84/opbh6HrMgPdbznSuYDREGzIgtS8=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=OQBViomQbwp7bZgr67nFX4bXyVvdihnfsX4qqLIJhw5cov8NwRlowbCfqCeB8B/TG vRZdctp8HDzZf5+MMfLQfGaLx8sLKTz+QD97JA9f/3ve2QDgYhC0hLH6dMJLQPhAiB mpAIGWRyRX/AroWWwl7GdtzWL5pw2DZ1FbKhQM1DCalokfCGrAWcRTTp67JDSuhVxS AQ4zKkwFJ5SSSBy1TDC7mw2jzppsjjBq202u+cwgkOE+I4z0mm1dat/+NS26OofQzA iIFxxdkBxEBRu6djTiz9092I9boXtgjVKklvBdRnPHpOicl4m8X4/d0eOZ3LVk21Ob sxvnPpw0oYzGA== Message-ID: Date: Thu, 29 Oct 2026 11:45:58 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] hugetlbfs: emit hugetlbfs_free_inode from ->destroy_inode() To: Joas Antonio dos Santos , Muchun Song , Oscar Salvador Cc: Andrew Morton , Hongbo Li , syzbot+91e1fc35f51774c479b2@syzkaller.appspotmail.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org References: <179324176522.32673.7602596908234555806@gmail.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: <179324176522.32673.7602596908234555806@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 6439F20006 X-Stat-Signature: oh1y1n63irt9aoqthdg8g7tywiomf6nh X-Rspam-User: X-Spam-Status: No, score=-17.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1793270764-222768 X-HE-Meta: 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 WQ4iYDBV 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 10/29/26 03:42, Joas Antonio dos Santos wrote: > hugetlbfs_free_inode() calls trace_hugetlbfs_free_inode(), and the > hugetlbfs__inode event class records inode->i_sb->s_dev. ->free_inode() > runs from an RCU callback (destroy_inode() queues i_callback() with > call_rcu()), and Documentation/filesystems/porting.rst says that this > callback "is *NOT* ordered wrt superblock destruction; as the matter of > fact, the superblock and all associated structures might be already > gone". put_super() frees the superblock with call_rcu() followed by a > workqueue item (destroy_super_rcu() -> destroy_super_work()). syzbot > hit this with the event enabled: > > BUG: KASAN: slab-use-after-free in trace_event_raw_event_hugetlbfs__inode+0x45b/0x4c0 include/trace/events/hugetlbfs.h:36 > Read of size 4 at addr ffff888038850010 by task syz-executor952/6134 > hugetlbfs_free_inode+0x15e/0x1f0 fs/hugetlbfs/inode.c:1182 > i_callback+0x46/0x80 fs/inode.c:317 > rcu_do_batch kernel/rcu/tree.c:2650 [inline] > rcu_core+0x5f0/0x1220 kernel/rcu/tree.c:2919 > Allocated by task 6134: > alloc_super fs/super.c:326 [inline] > sget_fc+0x1ba/0x1f60 fs/super.c:874 > hugetlbfs_get_tree+0x1e7/0x2b0 fs/hugetlbfs/inode.c:1431 > Freed by task 855: > kfree+0x22b/0x6d0 mm/slub.c:6923 > process_one_work+0xac7/0x1b10 kernel/workqueue.c:3495 > > Emit the event from hugetlbfs_destroy_inode() instead. destroy_inode() > calls ->destroy_inode() synchronously, before it queues the RCU > callback, while the superblock is still alive; hugetlbfs_destroy_inode() > already dereferences inode->i_sb there. ->free_inode() is left with > only the kmem_cache_free(). > > Fixes: 014ad7c42a69 ("hugetlbfs: use tracepoints in hugetlbfs functions.") > Reported-by: syzbot+91e1fc35f51774c479b2@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/all/6ae27525.5451848c.f7707.0001.GAE@google.com/ > Cc: stable@vger.kernel.org > Signed-off-by: Joas Antonio dos Santos > Assisted-by: Yaga Agent HackerSec Claude:claude-opus-5-5 > --- > Tested on net/main 94cea342e891 (arm64, QEMU, generic KASAN, tracing > enabled) with the syzbot C reproducer, which enables > events/hugetlbfs/hugetlbfs_free_inode and races hugetlbfs mounts and > lazy unmounts with open + unlink. Without this patch KASAN reports the > slab-use-after-free in trace_event_raw_event_hugetlbfs__inode() from > hugetlbfs_free_inode() <- i_callback() during the first 10 second run, > on 3 of 3 boots. With it, 12 runs over 2 boots are clean, and the trace > buffer still holds the hugetlbfs_free_inode events (about 46k per boot) > with valid dev numbers. fs/hugetlbfs/inode.o builds cleanly with W=1. > > The event now fires when the inode is destroyed instead of when its > memory goes back to the slab cache, one RCU grace period earlier; the > recorded fields are the same. > > fs/hugetlbfs/inode.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c > index 6656807..27a3937 100644 > --- a/fs/hugetlbfs/inode.c > +++ b/fs/hugetlbfs/inode.c > @@ -1179,12 +1179,16 @@ static struct inode *hugetlbfs_alloc_inode(struct super_block *sb) > > static void hugetlbfs_free_inode(struct inode *inode) > { > - trace_hugetlbfs_free_inode(inode); > kmem_cache_free(hugetlbfs_inode_cachep, HUGETLBFS_I(inode)); > } > > static void hugetlbfs_destroy_inode(struct inode *inode) > { > + /* > + * Not in ->free_inode(): that runs from an RCU callback, when the > + * superblock the event reads may already be freed. > + */ > + trace_hugetlbfs_free_inode(inode); > hugetlbfs_inc_free_inodes(HUGETLBFS_SB(inode->i_sb)); > } > Should we rename the tracepoint then? -- Cheers, David