From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 C46BD476CD7; Tue, 21 Jul 2026 17:53:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784656412; cv=none; b=pv1ofVEGIJkjGMZklaionU6QVvUsVOXpGLTu7d4Mgi2NLUBnNhoTWDNbbxLu0pnZY+uxD284aa6gKh/bosTVSisrL4MiW9nyYe1HEGVc+br8YsRQle21qU3TFIPkfXDlV/uJYiUKcGJ27ABt5eU+A/n+e5ZedBeuxxctomYOUcg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784656412; c=relaxed/simple; bh=6+C+FaqZHCyA/4YEFJbjQXbJuMFfW0pZSqpyvrWmhdg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Fpwc9uvhTDndbDJPdXtxqaSLdh3OarHtIOO/e5OV8XqP35gogXW2Epln79cDQWlXTn5wn0s40gqaeZ6rOrOsRp+YexLZ272o4w1HuWulAn5Dhuldnzx7fMJud902sWJZdzzelLVWuXyhNLDp/u9ImB7B6wNuoXN40TKpTEpKiP0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=1/Ym0GTa; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="1/Ym0GTa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3DDDD1F00A3E; Tue, 21 Jul 2026 17:53:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784656410; bh=A2dvRscgLhsxbb3sYivkFtd9S0jUeACffh9c7zYBjqQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=1/Ym0GTaGnD7gg6qw5fqDwFcVTTJacmX7B2k708KAp8+4Gb3go12Y8T9egR3tboji hXEPPYh1uGVDzMFls1MczcxbV+C1Vx0aRI0GkPkoIBdx9YpPVybIqymbW2AkM8Hg9b bns0jvhcgWC/mBDn2R7bp0SjCllQX5WsU1CLjxbo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Zhang Cen , Joseph Qi , Mark Fasheh , Joel Becker , Junxiao Bi , Changwei Ge , Jun Piao , Heming Zhao , Andrew Morton , Sasha Levin Subject: [PATCH 6.18 0334/1611] ocfs2: rebase copied fsdlm LVB pointers in locking_state Date: Tue, 21 Jul 2026 17:07:30 +0200 Message-ID: <20260721152522.614405781@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152514.750365251@linuxfoundation.org> References: <20260721152514.750365251@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zhang Cen [ Upstream commit 93612d48fa42b3d1a637eb9279e15281c611c000 ] The locking_state debugfs iterator snapshots struct ocfs2_lock_res by value under ocfs2_dlm_tracking_lock and later formats that copy in ocfs2_dlm_seq_show(). That is fine for the inline fields, but the userspace fsdlm stack stores the LVB through lksb_fsdlm.sb_lvbptr. Once the iterator drops the tracking lock, a copied non-NULL sb_lvbptr still points into the original lockres owner, so teardown can free that container before the debugfs dump walks the raw LVB bytes. Rebase the copied sb_lvbptr to the copied l_lksb before dumping the raw LVB. The seq snapshot already carries the inline LVB storage reserved in struct ocfs2_dlm_lksb, so the debugfs reader can dump the copied bytes without borrowing the original lockres lifetime. The buggy scenario involves two paths, with each column showing the order within that path: locking_state reader: lockres teardown: 1. ocfs2_dlm_seq_start()/next() 1. file release or another owner copies struct ocfs2_lock_res teardown reaches 2. ocfs2_dlm_seq_show() formats ocfs2_lock_res_free() the copied row 2. the lockres is removed from the 3. ocfs2_dlm_lvb() follows the tracking list copied sb_lvbptr 3. the owner frees the original lockres container Validation reproduced this kernel report: KASAN slab-use-after-free in ocfs2_dlm_seq_show+0x1bd/0x430 RIP: 0033:0x7f8ec4b1e29d The buggy address belongs to the object at ffff88810a1e0800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 368 bytes inside of freed 1024-byte region [ffff88810a1e0800, ffff88810a1e0c00) Read of size 1 Call trace: dump_stack_lvl+0x66/0xa0 print_report+0xce/0x630 ocfs2_dlm_seq_show+0x1bd/0x430 (fs/ocfs2/dlmglue.c:3137) srso_alias_return_thunk+0x5/0xfbef5 __virt_addr_valid+0x19f/0x330 kasan_report+0xe0/0x110 seq_read_iter+0x29d/0x790 seq_read+0x20a/0x280 find_held_lock+0x2b/0x80 rcu_read_unlock+0x18/0x70 full_proxy_read+0x9e/0xd0 vfs_read+0x12c/0x590 ksys_read+0xd2/0x170 do_user_addr_fault+0x65a/0x890 do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f Allocated by task stack: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0xaa/0xb0 ocfs2_file_open+0x13e/0x300 do_dentry_open+0x233/0x7f0 vfs_open+0x5a/0x1b0 path_openat+0x66d/0x1540 do_file_open+0x186/0x2b0 do_sys_openat2+0xce/0x150 __x64_sys_openat+0xd0/0x140 do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task stack: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x5f/0x80 kfree+0x313/0x590 ocfs2_file_release+0x138/0x260 __fput+0x1df/0x4b0 fput_close_sync+0xd2/0x170 __x64_sys_close+0x55/0x90 do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f Link: https://lore.kernel.org/20260525041726.4112882-1-rollkingzzc@gmail.com Fixes: cf4d8d75d8ab ("ocfs2: add fsdlm to stackglue") Assisted-by: Codex:gpt-5.5 Signed-off-by: Zhang Cen Reviewed-by: Joseph Qi Cc: Mark Fasheh Cc: Joel Becker Cc: Junxiao Bi Cc: Changwei Ge Cc: Jun Piao Cc: Heming Zhao Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin --- fs/ocfs2/dlmglue.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c index 92a6149da9c102..8ade51f7ffa8bb 100644 --- a/fs/ocfs2/dlmglue.c +++ b/fs/ocfs2/dlmglue.c @@ -3134,6 +3134,22 @@ static void *ocfs2_dlm_seq_next(struct seq_file *m, void *v, loff_t *pos) * - Add last pr/ex unlock times and first lock wait time in usecs */ #define OCFS2_DLM_DEBUG_STR_VERSION 4 + +/* + * The debug iterator snapshots lockres by value, so a userspace-stack LVB + * pointer copied from the original lockres must be rebased to the copied + * lksb before the dump walks the raw bytes. + */ +static void ocfs2_dlm_seq_rebase_lvb(struct ocfs2_lock_res *lockres) +{ + if (!ocfs2_stack_supports_plocks()) + return; + + if (lockres->l_lksb.lksb_fsdlm.sb_lvbptr) + lockres->l_lksb.lksb_fsdlm.sb_lvbptr = + (char *)&lockres->l_lksb + sizeof(struct dlm_lksb); +} + static int ocfs2_dlm_seq_show(struct seq_file *m, void *v) { int i; @@ -3191,6 +3207,7 @@ static int ocfs2_dlm_seq_show(struct seq_file *m, void *v) lockres->l_blocking); /* Dump the raw LVB */ + ocfs2_dlm_seq_rebase_lvb(lockres); lvb = ocfs2_dlm_lvb(&lockres->l_lksb); for(i = 0; i < DLM_LVB_LEN; i++) seq_printf(m, "0x%x\t", lvb[i]); -- 2.53.0