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 BF773351C2B for ; Mon, 20 Apr 2026 16:38:56 +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=1776703136; cv=none; b=hQQzR0GLdEWu4yKBJTA2Bbx+0E6cUxmQ+QXtMb28mzrRk5zRqAm4seHa0R1LApO4cVx2WtBDvWxx8zkjVemOPfEDPrv33UBSByPxVUk8oIZj+2Q1cHxasKEwg1LlG0jHBM2mO5+MFpV1t/ch121KCjippQnSBh9xLxxJv78dlT8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776703136; c=relaxed/simple; bh=iWi5dJ2irCazVhqGNNw6dxp02gxwHLNHW1qUw0AyiWo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ArCA8bqJTummitzEt3UU41aCtdlJrbTHIPoy9Wdpp3Wq+pnllYOo85RlFp3afwHXtp5hHkVCt+moRJV9yAss6Uvt+CzJUqkaCuMMKCtHgp2slf6Q1aU8EZH/F0xQdqkpV8Dux079v32Eop9D9eZt6fUpgs9/Y/PgrY1e7bOKY9A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=buBjgVRy; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="buBjgVRy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C49DFC2BCB4; Mon, 20 Apr 2026 16:38:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776703136; bh=iWi5dJ2irCazVhqGNNw6dxp02gxwHLNHW1qUw0AyiWo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=buBjgVRySnpbJWIV84O24He9OIXpaYpbkeBW9kyzOXImT7lYk/xNXzb1LuFVG+vN1 L/bZXLgdV+3rt4ePZ3w1XGSiXC11kq+GaG38d1mgPFZZpeZB132ro3GWfnINxyx+Em Pote9e1Zy8ZVYR9hUov5DTyPGZ30wgtRAPAyxSOJXnI4c1Oofg35fTtLf+e30Z+7Vz KDz8uElygOh+rKA2nfYbVK+S3hEETGXb7W0ryb+E6z3aspxqS4gjCWdD9nwIf6s2A7 IMSiZl5JxEbl+s187csKLdDCITRHYMTQzv5wQY3Zhk5xQziNecWO7/bJ8X3KS4BDoV YBdwx/mwx2MsA== From: Sasha Levin To: stable@vger.kernel.org Cc: Namjae Jeon , munan Huang , ChenXiaoSong , Steve French , Sasha Levin Subject: [PATCH 6.18.y 1/2] ksmbd: fix use-after-free in __ksmbd_close_fd() via durable scavenger Date: Mon, 20 Apr 2026 12:38:53 -0400 Message-ID: <20260420163854.1302592-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026042009-snarl-stagnant-e64b@gregkh> References: <2026042009-snarl-stagnant-e64b@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 --- fs/smb/server/vfs_cache.c | 41 ++++++++++++++++++++++++++++----------- 1 file changed, 30 insertions(+), 11 deletions(-) diff --git a/fs/smb/server/vfs_cache.c b/fs/smb/server/vfs_cache.c index 6ef116585af64..08f25a2d75416 100644 --- a/fs/smb/server/vfs_cache.c +++ b/fs/smb/server/vfs_cache.c @@ -370,9 +370,11 @@ static void __ksmbd_close_fd(struct ksmbd_file_table *ft, struct ksmbd_file *fp) * 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 ksmbd_tree_connect *tcon, 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 ksmbd_tree_connect *tcon, } 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_work *work, struct ksmbd_file *fp) { 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_work *work, struct ksmbd_file *fp) 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_work *work, struct ksmbd_file *fp) } 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; } -- 2.53.0