From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 C8F5519A288; Fri, 24 Apr 2026 13:41:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777038109; cv=none; b=c0CTCoKKo+kvPLMX/dfdCNV+mmhlZm6gewdM3m5hMjKEUVclOxU34/bDlpsGrmuFhmqaIX4NoorKIsSB06DZE3yNwZH35Rq9EEt5VxATtS5ZDBefe/KX7GDBr1MGxD9+0gxcQ1Eldz9r7y5nKO0CbCvrHJp4byAvYLG+r0AUcD0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777038109; c=relaxed/simple; bh=v3sGPDG3byw5YJRQBAC3NY1ApORNJ8Wn5sPZyvPuqFI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rzu3V1+iuF0YqxRw6peE4Ye5/5DyE3kteNEJ3qP/BDyEfTEwBudBfGN7ZmuasGdYICeFGwx4XXGWYxQFwTr8M7qGKisBPNFoIil2pYPpirFu+AO9TaRBelJDGoVRw8BYv5671GvvsZhfQ4utEqlE5+4RESTHl4U2wuCvbEg1kAM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=HAiVhod0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="HAiVhod0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5EB24C19425; Fri, 24 Apr 2026 13:41:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1777038109; bh=v3sGPDG3byw5YJRQBAC3NY1ApORNJ8Wn5sPZyvPuqFI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HAiVhod0t4zlTG0hsj7B1je6WlU2rM13YCFX1a4wFzvy87rjvXEwvdmH43ttE5R6t WybF67ViHCV4ks/bBk95HQ1KSh83+hlnyjKt9hpnJQAVmZDKUAEk6WDNI5TQbPLltH 7h2xPpsnJjK0aw2Lfjf12jGQ1ZaPhTmxwHxiW6Zo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, munan Huang , ChenXiaoSong , Namjae Jeon , Steve French , Sasha Levin Subject: [PATCH 6.18 08/55] ksmbd: fix use-after-free in __ksmbd_close_fd() via durable scavenger Date: Fri, 24 Apr 2026 15:30:47 +0200 Message-ID: <20260424132431.770102631@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260424132430.006424517@linuxfoundation.org> References: <20260424132430.006424517@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org 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: Namjae Jeon [ Upstream commit 235e32320a470fcd3998fb3774f2290a0eb302a1 ] When a durable file handle survives session disconnect (TCP close without SMB2_LOGOFF), session_fd_check() sets fp->conn = NULL to preserve the handle for later reconnection. However, it did not clean up the byte-range locks on fp->lock_list. Later, when the durable scavenger thread times out and calls __ksmbd_close_fd(NULL, fp), the lock cleanup loop did: spin_lock(&fp->conn->llist_lock); This caused a slab use-after-free because fp->conn was NULL and the original connection object had already been freed by ksmbd_tcp_disconnect(). The root cause is asymmetric cleanup: lock entries (smb_lock->clist) were left dangling on the freed conn->lock_list while fp->conn was nulled out. To fix this issue properly, we need to handle the lifetime of smb_lock->clist across three paths: - Safely skip clist deletion when list is empty and fp->conn is NULL. - Remove the lock from the old connection's lock_list in session_fd_check() - Re-add the lock to the new connection's lock_list in ksmbd_reopen_durable_fd(). Fixes: c8efcc786146 ("ksmbd: add support for durable handles v1/v2") Co-developed-by: munan Huang Signed-off-by: munan Huang Reviewed-by: ChenXiaoSong Signed-off-by: Namjae Jeon Signed-off-by: Steve French Stable-dep-of: 49110a8ce654 ("ksmbd: validate owner of durable handle on reconnect") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/smb/server/vfs_cache.c | 41 ++++++++++++++++++++++++++++++----------- 1 file changed, 30 insertions(+), 11 deletions(-) --- a/fs/smb/server/vfs_cache.c +++ b/fs/smb/server/vfs_cache.c @@ -370,9 +370,11 @@ static void __ksmbd_close_fd(struct ksmb * there are not accesses to fp->lock_list. */ list_for_each_entry_safe(smb_lock, tmp_lock, &fp->lock_list, flist) { - spin_lock(&fp->conn->llist_lock); - list_del(&smb_lock->clist); - spin_unlock(&fp->conn->llist_lock); + if (!list_empty(&smb_lock->clist) && fp->conn) { + spin_lock(&fp->conn->llist_lock); + list_del(&smb_lock->clist); + spin_unlock(&fp->conn->llist_lock); + } list_del(&smb_lock->flist); locks_free_lock(smb_lock->fl); @@ -902,6 +904,7 @@ static bool session_fd_check(struct ksmb struct ksmbd_inode *ci; struct oplock_info *op; struct ksmbd_conn *conn; + struct ksmbd_lock *smb_lock, *tmp_lock; if (!is_reconnectable(fp)) return false; @@ -918,6 +921,12 @@ static bool session_fd_check(struct ksmb } up_write(&ci->m_lock); + list_for_each_entry_safe(smb_lock, tmp_lock, &fp->lock_list, flist) { + spin_lock(&fp->conn->llist_lock); + list_del_init(&smb_lock->clist); + spin_unlock(&fp->conn->llist_lock); + } + fp->conn = NULL; fp->tcon = NULL; fp->volatile_id = KSMBD_NO_FID; @@ -996,6 +1005,9 @@ int ksmbd_reopen_durable_fd(struct ksmbd { struct ksmbd_inode *ci; struct oplock_info *op; + struct ksmbd_conn *conn = work->conn; + struct ksmbd_lock *smb_lock; + unsigned int old_f_state; if (!fp->is_durable || fp->conn || fp->tcon) { pr_err("Invalid durable fd [%p:%p]\n", fp->conn, fp->tcon); @@ -1007,9 +1019,23 @@ int ksmbd_reopen_durable_fd(struct ksmbd return -EBADF; } - fp->conn = work->conn; + old_f_state = fp->f_state; + fp->f_state = FP_NEW; + __open_id(&work->sess->file_table, fp, OPEN_ID_TYPE_VOLATILE_ID); + if (!has_file_id(fp->volatile_id)) { + fp->f_state = old_f_state; + return -EBADF; + } + + fp->conn = conn; fp->tcon = work->tcon; + list_for_each_entry(smb_lock, &fp->lock_list, flist) { + spin_lock(&conn->llist_lock); + list_add_tail(&smb_lock->clist, &conn->lock_list); + spin_unlock(&conn->llist_lock); + } + ci = fp->f_ci; down_write(&ci->m_lock); list_for_each_entry_rcu(op, &ci->m_op_list, op_entry) { @@ -1020,13 +1046,6 @@ int ksmbd_reopen_durable_fd(struct ksmbd } up_write(&ci->m_lock); - fp->f_state = FP_NEW; - __open_id(&work->sess->file_table, fp, OPEN_ID_TYPE_VOLATILE_ID); - if (!has_file_id(fp->volatile_id)) { - fp->conn = NULL; - fp->tcon = NULL; - return -EBADF; - } return 0; }