From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=115.124.30.132 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793191699; b=hXm62N2DxkKTjMRA+cVVQq6RSJGWxwn9kelALECcsSDsdUQ4+yqum4q1+Xw7yJR26MEE 26bOdHEbZIE750m4lUELTeiqgaZPRNelPScZE6ifX3BWDSa4uc1YEfpj653c2cPgaYSdU 4zP5tseVTp+smSTfOYtVGsqH4JxCLw93hxXoBPpvpH94el+2Xy1PBsbeEldFDjt3vQT6W A3dmHtolW8YtWF5B9MrFtEByvDGEinHWq8R838fC7FTR11zDQXE1vxwl1CsoI/Ncx8Oqw 5WuptEhf20+lGAxPbGOJ/DU7dAKb12lqjgjLYLFlOOia0OXuEl6HsywHCzpwVP1ff9Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793191699; h=DMARC-Filter:DKIM-Signature:X-Alimail-AntiSpam:Received:Message-ID: Date:MIME-Version:User-Agent:Subject:To:Cc:References:From: In-Reply-To:Content-Type:Content-Transfer-Encoding; bh=/rp10C9vmYrvZ8n2ETCONDZuve+pgclYyA15cGXRQ9U=; b=PMSHRgR4+YbclU+jvr9bSEIrHUL1L7Y+IPc9kX4CCgXJzu72w2Gxn0R0TNgYWvNw6O5a wjJIa3/PQkFv3FjkcAtUVhvON46wr/tNjXuKXG0bIN6CqsV6HZglN0HlGWzu+kT+YQUGo vkImcwe+piwILM/aTNzqQvz1AU9u1+d9TlLtH1W22WZCEImzW4WLyvyjPp6z7lSPKiYkq HkT9ykfdAKWyB6aufMGoqrxzKaeEOrP9bn5YTfTr6r7uQ3QFcgY8jSM/fI/YQZq01z+HP F09lAM/qC41c9vGk6shAbsQSjUy4seWJMic1MnyoMtq/ZwZh26xLz3ZpNDU7j1MppdA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass header.d=linux.alibaba.com header.i=@linux.alibaba.com header.a=rsa-sha256 header.s=default header.b=b4txhJpw; arc=none smtp.remote-ip=115.124.30.132 Received: from out30-132.freemail.mail.aliyun.com (out30-132.freemail.mail.aliyun.com [115.124.30.132]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C1D73606A31A; Wed, 28 Oct 2026 12:48:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org C1D73606A31A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.a=rsa-sha256 header.s=default header.b=b4txhJpw DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1793191688; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=/rp10C9vmYrvZ8n2ETCONDZuve+pgclYyA15cGXRQ9U=; b=b4txhJpwHmZZaVNsrVSG6XnzxVadk3HQPSZdFNXPAuG4r11vy5T6zenr8uDb5KeazgXNx39vcZyCJr01z/vert8PBe4SJY6J2+lIgXZJYrmZby67vsinjeOcStpPP0nfgGDTmS7sjMB7BKiFCTNhCXN6UHDQca9tJ+7XpPvTLWg= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R191e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033037026112;MF=joseph.qi@linux.alibaba.com;NM=1;PH=DS;RN=9;SR=0;TI=SMTPD_---0XDgpOyF_1793191687; Received: from 30.221.129.127(mailfrom:joseph.qi@linux.alibaba.com fp:SMTPD_---0XDgpOyF_1793191687 cluster:ay36) by smtp.aliyun-inc.com; Wed, 28 Oct 2026 20:48:08 +0800 Message-ID: Date: Wed, 28 Oct 2026 20:48:07 +0800 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 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] ocfs2: advance locking_state through the live cursor To: Cen Zhang Cc: mark@fasheh.com, jlbec@evilplan.org, heming.zhao@suse.com, ocfs2-devel@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org, baijiaju1990@gmail.com, jjzuming@gmail.com References: From: Joseph Qi In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/26/26 10:00 PM, Cen Zhang wrote: > locking_state copies each lock resource under ocfs2_dlm_tracking_lock > so its containing inode or quota object can be freed during the dump. > The copied l_debug_list pointers do not have that lifetime protection. > Yet ocfs2_dlm_seq_next() follows them to find the next record. > > Remounting read-only can free a quota-info object while a debugfs read > is between the snapshot and the next iterator callback: > > locking_state reader Quota suspension > -------------------- ---------------- > snapshot current lock resource > copy l_debug_list.next > remove next resource from live list > free quota-info object > seq_next(): follow copied link > read freed lock resource > > Advance through the live dummy cursor instead. List removal updates its > links under the tracking lock. Position it after the resource being > copied before releasing the lock, and never walk the snapshot's links. > Rebuild the cursor from the requested position in seq_start() so a > seq_file buffer retry or seek starts at that record again. seq_lseek() does not pass the target to ->start. It calls traverse(), which resets the index and walks forward through ->next instead. > > KASAN report as below: > > BUG: KASAN: slab-use-after-free in ocfs2_dlm_next_res.isra.0+0x1b1/0x1d0 > Read of size 8 at addr ffff888117ea9838 by task python3/489 > > CPU: 3 UID: 0 PID: 489 Comm: python3 Not tainted 7.3.0-rc4-next-20260921-pmb-bt-functional-v1+ #1 PREEMPT(lazy) > 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 > Call Trace: > > dump_stack_lvl+0x93/0xd0 > print_report+0xce/0x630 > ? ocfs2_dlm_next_res.isra.0+0x1b1/0x1d0 > ? srso_alias_return_thunk+0x5/0xfbef5 > ? __virt_addr_valid+0x20e/0x420 > ? ocfs2_dlm_next_res.isra.0+0x1b1/0x1d0 > kasan_report+0xe0/0x110 > ? ocfs2_dlm_next_res.isra.0+0x1b1/0x1d0 > ocfs2_dlm_next_res.isra.0+0x1b1/0x1d0 > ? __pfx_ocfs2_dlm_next_res.isra.0+0x10/0x10 > ? __pfx_do_raw_spin_lock+0x10/0x10 > ocfs2_dlm_seq_next+0xb8/0x4c0 > ? srso_alias_return_thunk+0x5/0xfbef5 > seq_read_iter+0x92f/0x1110 > ? srso_alias_return_thunk+0x5/0xfbef5 > seq_read+0x362/0x5a0 > ? __pfx_seq_read+0x10/0x10 > ? srso_alias_return_thunk+0x5/0xfbef5 > ? srso_alias_return_thunk+0x5/0xfbef5 > ? selinux_file_permission+0x11d/0x540 > full_proxy_read+0x11f/0x180 > ? __pfx_full_proxy_read+0x10/0x10 > vfs_read+0x1a0/0xc20 > ? srso_alias_return_thunk+0x5/0xfbef5 > ? kmem_cache_free+0x242/0x580 > ? __pfx_vfs_read+0x10/0x10 > ? srso_alias_return_thunk+0x5/0xfbef5 > ? putname+0x93/0xe0 > ? srso_alias_return_thunk+0x5/0xfbef5 > ? do_sys_openat2+0x12a/0x1b0 > ? __pfx_do_sys_openat2+0x10/0x10 > ksys_read+0x111/0x200 > ? __pfx_ksys_read+0x10/0x10 > ? irqentry_exit+0xbe/0x820 > ? srso_alias_return_thunk+0x5/0xfbef5 > ? trace_hardirqs_on_prepare+0x11d/0x150 > do_syscall_64+0x114/0x620 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7f0266dbb687 > Code: 48 89 fa 4c 89 df e8 58 b3 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff > RSP: 002b:00007ffccf76fc40 EFLAGS: 00000202 ORIG_RAX: 0000000000000000 > RAX: ffffffffffffffda RBX: 00007f0266d27780 RCX: 00007f0266dbb687 > RDX: 0000000000000001 RSI: 00007f0266a53200 RDI: 0000000000000004 > RBP: 00007f0266d27700 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000001 > R13: 00007f0266a53200 R14: 0000000000000004 R15: 00007f0266b651e0 > > > Allocated by task 547: > kasan_save_stack+0x33/0x60 > kasan_save_track+0x14/0x30 > __kasan_kmalloc+0xaa/0xb0 > __kmalloc_cache_noprof+0x28d/0x610 > ocfs2_local_read_info+0x181/0x1580 > dquot_load_quota_sb+0x68b/0x1000 > dquot_load_quota_inode+0x227/0x3e0 > ocfs2_enable_quotas+0x27c/0x520 > ocfs2_fill_super+0x21f9/0x38f0 > get_tree_bdev_flags+0x35d/0x5f0 > vfs_get_tree+0x93/0x320 > fc_mount+0x1d/0x200 > path_mount+0x592/0x1e00 > __x64_sys_mount+0x24b/0x2d0 > do_syscall_64+0x114/0x620 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > Freed by task 577: > kasan_save_stack+0x33/0x60 > kasan_save_track+0x14/0x30 > kasan_save_free_info+0x3b/0x60 > __kasan_slab_free+0x5f/0x80 > kfree+0x308/0x580 > ocfs2_local_free_info+0x47b/0x800 > dquot_disable+0x5d9/0x17a0 > ocfs2_susp_quotas.isra.0+0x22c/0x2b0 > ocfs2_reconfigure+0x284/0xd00 > reconfigure_super+0x3ca/0xa70 > path_mount+0x16ae/0x1e00 > __x64_sys_mount+0x24b/0x2d0 > do_syscall_64+0x114/0x620 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > The buggy address belongs to the object at ffff888117ea9800 > which belongs to the cache kmalloc-1k of size 1024 > The buggy address is located 56 bytes inside of > freed 1024-byte region [ffff888117ea9800, ffff888117ea9c00) > > The buggy address belongs to the physical page: > page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x117ea8 > head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 > flags: 0x200000000000040(head|node=0|zone=2) > page_type: f5(slab) > raw: 0200000000000040 ffff888100042dc0 dead000000000100 dead000000000122 > raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000 > head: 0200000000000040 ffff888100042dc0 dead000000000100 dead000000000122 > head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000 > head: 0200000000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff > head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff888117ea9700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff888117ea9780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > >ffff888117ea9800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ^ > ffff888117ea9880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff888117ea9900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ================================================================== > > Fixes: ccd979bdbce9 ("[PATCH] OCFS2: The Second Oracle Cluster Filesystem") > Cc: stable@vger.kernel.org > Assisted-by: LLM > Signed-off-by: Cen Zhang > > --- > fs/ocfs2/dlmglue.c | 17 +++++++++++++---- > 1 file changed, 13 insertions(+), 4 deletions(-) > > diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c > index 88d946466083..5e05e98fb9cb 100644 > --- a/fs/ocfs2/dlmglue.c > +++ b/fs/ocfs2/dlmglue.c > @@ -3101,10 +3101,19 @@ static struct ocfs2_lock_res *ocfs2_dlm_next_res(struct ocfs2_lock_res *start, > static void *ocfs2_dlm_seq_start(struct seq_file *m, loff_t *pos) > { > struct ocfs2_dlm_seq_priv *priv = m->private; > - struct ocfs2_lock_res *iter; > + struct ocfs2_lock_res *iter = NULL; > + struct ocfs2_lock_res *dummy = &priv->p_iter_res; > + loff_t n; > > spin_lock(&ocfs2_dlm_tracking_lock); > - iter = ocfs2_dlm_next_res(&priv->p_iter_res, priv); > + list_move(&dummy->l_debug_list, > + &priv->p_dlm_debug->d_lockres_tracking); > + for (n = 0; n <= *pos; n++) { > + iter = ocfs2_dlm_next_res(dummy, priv); > + if (!iter) > + break; > + list_move(&dummy->l_debug_list, &iter->l_debug_list); > + } seq_read_iter() calls ->start once per read and its buffer is a page, so reading the whole file with N tracked resources re-enters this loop about N/R times at increasing *pos, and a single late ->start holds the lock for that many list_move() calls. And ocfs2_dlm_tracking_lock is taken on every lock resource create and destroy. So I'm not sure the lock hold time on it is acceptable. Thanks, Joseph > if (iter) { > /* Since lockres' have the lifetime of their container > * (which can be inodes, ocfs2_supers, etc) we want to > @@ -3128,12 +3137,12 @@ static void ocfs2_dlm_seq_stop(struct seq_file *m, void *v) > static void *ocfs2_dlm_seq_next(struct seq_file *m, void *v, loff_t *pos) > { > struct ocfs2_dlm_seq_priv *priv = m->private; > - struct ocfs2_lock_res *iter = v; > + struct ocfs2_lock_res *iter; > struct ocfs2_lock_res *dummy = &priv->p_iter_res; > > (*pos)++; > spin_lock(&ocfs2_dlm_tracking_lock); > - iter = ocfs2_dlm_next_res(iter, priv); > + iter = ocfs2_dlm_next_res(dummy, priv); > list_del_init(&dummy->l_debug_list); > if (iter) { > list_add(&dummy->l_debug_list, &iter->l_debug_list);