From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relayaws-01.paragon-software.com (relayaws-01.paragon-software.com [35.157.23.187]) (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 063F73CFF5A for ; Fri, 22 May 2026 13:50:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=35.157.23.187 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779457861; cv=none; b=aEsgzCvuIfnN5mPEDjy2tcc9bcVMM8oqLj01g3KDWRGIOWPpaYV2Zm7kZWpVQF4bP3iGiriiy+bG6O31HlQIxjG9S2zpYNpdBvS9FbFK1N5xiRObBozmN23BHnk9+Xd1jOIS+UyFMV0vv2PZlrwSCgfUCpKV0T6ZsVM54IjhQNk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779457861; c=relaxed/simple; bh=PlRuU8u8bHTnptif2bZpA2rW4SwBQ597unWHpGjQHEs=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=UQ/xo//FNmXFc4LxP7qfrUkNoXgI5BawLZb0dGNeI+9b3XiS/7T7nb96XUapui44fovtKtBlcfz68Nyn1nCyfZ9UY9gpO6LwhNUHp4uH0GuqJSE/iBObiuk3LLbXux6yj5NgaMnVuckZQtnoSki5HQzDRDPhfkbVRBm2eXYvg2A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=paragon-software.com; spf=pass smtp.mailfrom=paragon-software.com; dkim=pass (1024-bit key) header.d=paragon-software.com header.i=@paragon-software.com header.b=nk/BvEPx; arc=none smtp.client-ip=35.157.23.187 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=paragon-software.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=paragon-software.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=paragon-software.com header.i=@paragon-software.com header.b="nk/BvEPx" Received: from relayfre-01.paragon-software.com (relayfre-01.paragon-software.com [176.12.100.13]) by relayaws-01.paragon-software.com (Postfix) with ESMTPS id B605C1D3E; Fri, 22 May 2026 13:51:01 +0000 (UTC) Authentication-Results: relayaws-01.paragon-software.com; dkim=pass (1024-bit key; unprotected) header.d=paragon-software.com header.i=@paragon-software.com header.b=nk/BvEPx; dkim-atps=neutral Received: from dlg2.mail.paragon-software.com (vdlg-exch-02.paragon-software.com [172.30.1.105]) by relayfre-01.paragon-software.com (Postfix) with ESMTPS id 21FD22203; Fri, 22 May 2026 13:50:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=paragon-software.com; s=mail; t=1779457854; bh=V7eTMocB/EJucs5glx068x+vg66gfhYOXhK2w/egizE=; h=Date:Subject:To:CC:References:From:In-Reply-To; b=nk/BvEPxExNhnTh4uv69Q3fN+uGWDm5xFLEDHwi1pfH+qlrHVDy3kq431CNL9we86 RGF2qWgZbKSWXUz6KMqR4JesygdZFJy6ni0cVygK1wIpJJeA9zMvH4PDEB/md0B6yS Wn8Mjxcv6mnjGO+Mrx742INjtt5e6RcHxspCpNDo= Received: from [192.168.95.128] (172.30.20.156) by vdlg-exch-02.paragon-software.com (172.30.1.105) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.7; Fri, 22 May 2026 16:50:52 +0300 Message-ID: Date: Fri, 22 May 2026 15:50:51 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] fs/ntfs3: hold ni_lock across readdir metadata walk To: ZhengYuan Huang CC: , , , , References: <20260427072650.300732-1-gality369@gmail.com> Content-Language: en-US From: Konstantin Komarov In-Reply-To: <20260427072650.300732-1-gality369@gmail.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: vobn-exch-01.paragon-software.com (172.30.72.13) To vdlg-exch-02.paragon-software.com (172.30.1.105) On 4/27/26 09:26, ZhengYuan Huang wrote: > [You don't often get email from gality369@gmail.com. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ] > > [BUG] > KASAN reports a slab-use-after-free during getdents(2): > > BUG: KASAN: slab-use-after-free in ntfs_read_mft fs/ntfs3/inode.c:79 [inline] > BUG: KASAN: slab-use-after-free in ntfs_iget5+0x59b/0x3450 fs/ntfs3/inode.c:541 > Read of size 2 at addr ffff88800b7a5a4e by task syz.0.1061/2354 > > Call Trace: > __dump_stack lib/dump_stack.c:94 [inline] > dump_stack_lvl+0xbe/0x130 lib/dump_stack.c:120 > print_address_description mm/kasan/report.c:378 [inline] > print_report+0xd1/0x650 mm/kasan/report.c:482 > kasan_report+0xfb/0x140 mm/kasan/report.c:595 > __asan_report_load2_noabort+0x14/0x30 mm/kasan/report_generic.c:379 > ntfs_read_mft fs/ntfs3/inode.c:79 [inline] > ntfs_iget5+0x59b/0x3450 fs/ntfs3/inode.c:541 > ntfs_dir_emit fs/ntfs3/dir.c:337 [inline] > ntfs_read_hdr+0x714/0x930 fs/ntfs3/dir.c:385 > ntfs_readdir+0xaad/0x1010 fs/ntfs3/dir.c:458 > iterate_dir+0x276/0x9e0 fs/readdir.c:108 > __do_sys_getdents fs/readdir.c:326 [inline] > __se_sys_getdents fs/readdir.c:312 [inline] > __x64_sys_getdents+0x143/0x290 fs/readdir.c:312 > ... > > Allocated by task 2160: > kasan_save_stack+0x39/0x70 mm/kasan/common.c:56 > kasan_save_track+0x14/0x40 mm/kasan/common.c:77 > kasan_save_alloc_info+0x37/0x60 mm/kasan/generic.c:573 > poison_kmalloc_redzone mm/kasan/common.c:400 [inline] > __kasan_kmalloc+0xc3/0xd0 mm/kasan/common.c:417 > kasan_kmalloc include/linux/kasan.h:262 [inline] > __do_kmalloc_node mm/slub.c:5650 [inline] > __kmalloc_noprof+0x2bd/0x900 mm/slub.c:5662 > kmalloc_noprof include/linux/slab.h:961 [inline] > mi_init+0x9d/0x110 fs/ntfs3/record.c:105 > mi_format_new+0x6b/0x500 fs/ntfs3/record.c:422 > ni_add_subrecord+0x129/0x540 fs/ntfs3/frecord.c:321 > ntfs_look_free_mft+0x238/0xd90 fs/ntfs3/fsntfs.c:715 > ni_create_attr_list+0x8e6/0x1690 fs/ntfs3/frecord.c:826 > ni_ins_attr_ext+0x5ec/0x9d0 fs/ntfs3/frecord.c:924 > ni_insert_attr+0x2bf/0x830 fs/ntfs3/frecord.c:1091 > ni_insert_resident+0xec/0x3d0 fs/ntfs3/frecord.c:1475 > ni_add_name+0x4b2/0x8a0 fs/ntfs3/frecord.c:2987 > ni_rename+0xa6/0x160 fs/ntfs3/frecord.c:3026 > ntfs_rename+0xa19/0xe00 fs/ntfs3/namei.c:332 > vfs_rename+0xd42/0x1d50 fs/namei.c:5216 > do_renameat2+0x715/0xb60 fs/namei.c:5364 > __do_sys_rename fs/namei.c:5411 [inline] > __se_sys_rename fs/namei.c:5409 [inline] > __x64_sys_rename+0x83/0xb0 fs/namei.c:5409 > x64_sys_call+0x8c4/0x26a0 arch/x86/include/generated/asm/syscalls_64.h:83 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0x93/0xf80 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x76/0x7e > > Freed by task 85: > kasan_save_stack+0x39/0x70 mm/kasan/common.c:56 > kasan_save_track+0x14/0x40 mm/kasan/common.c:77 > __kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:587 > kasan_save_free_info mm/kasan/kasan.h:406 [inline] > poison_slab_object mm/kasan/common.c:252 [inline] > __kasan_slab_free+0x6f/0xa0 mm/kasan/common.c:284 > kasan_slab_free include/linux/kasan.h:234 [inline] > slab_free_hook mm/slub.c:2543 [inline] > slab_free mm/slub.c:6642 [inline] > kfree+0x2bf/0x6b0 mm/slub.c:6849 > mi_clear fs/ntfs3/ntfs_fs.h:1107 [inline] > mi_put+0x10e/0x1a0 fs/ntfs3/record.c:97 > ni_write_inode+0x479/0x2a00 fs/ntfs3/frecord.c:3320 > ntfs3_write_inode+0x51/0x70 fs/ntfs3/inode.c:1042 > write_inode fs/fs-writeback.c:1564 [inline] > __writeback_single_inode+0x8c9/0xc30 fs/fs-writeback.c:1784 > writeback_sb_inodes+0x5e6/0xf60 fs/fs-writeback.c:2015 > __writeback_inodes_wb+0x10c/0x2d0 fs/fs-writeback.c:2086 > wb_writeback+0x63f/0x900 fs/fs-writeback.c:2197 > wb_check_old_data_flush fs/fs-writeback.c:2301 [inline] > wb_do_writeback fs/fs-writeback.c:2354 [inline] > wb_workfn+0x8cc/0xd60 fs/fs-writeback.c:2382 > process_one_work+0x8e0/0x1980 kernel/workqueue.c:3263 > process_scheduled_works kernel/workqueue.c:3346 [inline] > worker_thread+0x683/0xf80 kernel/workqueue.c:3427 > kthread+0x3f0/0x850 kernel/kthread.c:463 > ret_from_fork+0x50f/0x610 arch/x86/kernel/process.c:158 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 > > The faulting address sits 590 bytes inside a freed kmalloc-1k object > allocated by ni_add_subrecord() and freed from ni_write_inode() > writeback. > > [CAUSE] > ntfs_readdir() loads all subrecords once, but then drops ni_lock() > before it starts walking the directory metadata through ntfs_read_hdr(). > That leaves the current NTFS_DE pointer backed by parent-directory > subrecord memory that concurrent writeback is still allowed to compact > and free. > > The later ntfs_dir_emit() -> ntfs_iget5() call exposes the stale e->ref, > but the lifetime bug starts earlier: readdir is still consuming > parent-directory metadata after releasing the lock that protects it. > > [FIX] > Keep ni_lock() held from the point where ntfs_readdir() starts > consuming the directory metadata until the walk over root/index entries > is finished. > > This closes the parent-directory lifetime hole directly and keeps the > existing readdir d_type behaviour unchanged. > > Signed-off-by: ZhengYuan Huang > --- > fs/ntfs3/dir.c | 22 ++++++++++++++++------ > 1 file changed, 16 insertions(+), 6 deletions(-) > > diff --git a/fs/ntfs3/dir.c b/fs/ntfs3/dir.c > index d99ab086ef6f..a052ba9250e7 100644 > --- a/fs/ntfs3/dir.c > +++ b/fs/ntfs3/dir.c > @@ -489,10 +489,17 @@ static int ntfs_readdir(struct file *file, struct dir_context *ctx) > goto out; > } > > + /* > + * Keep directory metadata stable for the whole walk. Loading subrecords > + * once is not enough if concurrent writeback can still compact ATTR_LIST > + * entries and free the record that ntfs_read_hdr() is currently walking. > + */ > + ni_lock(ni); > + > root = indx_get_root(&ni->dir, ni, NULL, NULL); > if (!root) { > err = -EINVAL; > - goto out; > + goto out_unlock; > } > > if (pos >= sbi->record_size) { > @@ -503,7 +510,7 @@ static int ntfs_readdir(struct file *file, struct dir_context *ctx) > */ > err = ntfs_read_hdr(sbi, ni, &root->ihdr, 0, pos, name, ctx); > if (err) > - goto out; > + goto out_unlock; > bit = 0; > } > > @@ -514,7 +521,7 @@ static int ntfs_readdir(struct file *file, struct dir_context *ctx) > /* Get the next used index. */ > err = indx_used_bit(&ni->dir, ni, &bit); > if (err) > - goto out; > + goto out_unlock; > > if (bit == MINUS_ONE_T) { > /* no more used indexes. end of dir. */ > @@ -524,13 +531,13 @@ static int ntfs_readdir(struct file *file, struct dir_context *ctx) > if (bit >= max_bit) { > /* Corrupted directory. */ > err = -EINVAL; > - goto out; > + goto out_unlock; > } > > err = indx_read_ra(&ni->dir, ni, bit << ni->dir.idx2vbn_bits, > &node, &file->f_ra); > if (err) > - goto out; > + goto out_unlock; > > /* > * Add each name from index in 'ctx'. > @@ -539,9 +546,12 @@ static int ntfs_readdir(struct file *file, struct dir_context *ctx) > ((u64)bit << index_bits) + sbi->record_size, > pos, name, ctx); > if (err) > - goto out; > + goto out_unlock; > } > > +out_unlock: > + ni_unlock(ni); > + > out: > kfree(name); > put_indx_node(node); > -- > 2.49.0 Hello, Sorry for the delay. Your patch was applied, thank you. Regards, Konstantin