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 2A1CDB663; Tue, 8 Apr 2025 12:40:24 +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=1744116024; cv=none; b=hau9s9gKZlRHbDtfqbl70cld+3bvag+MzZtrAx/4RYtMV+MBcZkhRJlOHo1108sm8MPGj4kBGVCvYKesOZzBdHkr8N7mT+ZZRn0E6tQe6QcZzbXUizy9VMb5us6XflCMS8zO+LRVUh8xXnbrMDA26bNp7R7uder9ELiv7FF1QdQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744116024; c=relaxed/simple; bh=Wn8q03GMf4uy4unTIE+JrSdBjh2BZ1z7wLacNQP5YGk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=YyrGZF3LMui1nxENPv5YWQ+WWY+FueDCEIm7PUMY7UWsIudW6r0DHxU46JnBCQFrd4e7yky2KiWNWIQ3tdOejP3XvuIxS0eF6rNg3F0Izssv5El31ZdOkX0z5ntydD7Oz4uZEB9etCK43wUD0rj7mudttJ+SXNbr++JbXdM2euc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=F8eL1oZO; 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="F8eL1oZO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AEE69C4CEE5; Tue, 8 Apr 2025 12:40:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1744116024; bh=Wn8q03GMf4uy4unTIE+JrSdBjh2BZ1z7wLacNQP5YGk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=F8eL1oZOfHq8FDJh2WtNi99WgELqYfVCH/iBR0OqTT+2PWBgweRkQ83qXL1r52xal jM4CHQl4UCQCWJunqmZt12p4n4h2AABY8h1RLfYR1TqllsSULuZrJwzhcd6uxwn9hH JOfwnDdGk1ASrmPg2+RWnaP/K9mU06B9ZK2dEpN4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sean Heelan , Namjae Jeon , Steve French Subject: [PATCH 6.1 191/204] ksmbd: fix session use-after-free in multichannel connection Date: Tue, 8 Apr 2025 12:52:01 +0200 Message-ID: <20250408104825.917884427@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250408104820.266892317@linuxfoundation.org> References: <20250408104820.266892317@linuxfoundation.org> User-Agent: quilt/0.68 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 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Namjae Jeon commit fa4cdb8cbca7d6cb6aa13e4d8d83d1103f6345db upstream. There is a race condition between session setup and ksmbd_sessions_deregister. The session can be freed before the connection is added to channel list of session. This patch check reference count of session before freeing it. Cc: stable@vger.kernel.org Reported-by: Sean Heelan Signed-off-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman --- fs/smb/server/auth.c | 4 ++-- fs/smb/server/mgmt/user_session.c | 14 ++++++++------ fs/smb/server/smb2pdu.c | 7 ++++--- 3 files changed, 14 insertions(+), 11 deletions(-) --- a/fs/smb/server/auth.c +++ b/fs/smb/server/auth.c @@ -1010,9 +1010,9 @@ static int ksmbd_get_encryption_key(stru ses_enc_key = enc ? sess->smb3encryptionkey : sess->smb3decryptionkey; - if (enc) - ksmbd_user_session_get(sess); memcpy(key, ses_enc_key, SMB3_ENC_DEC_KEY_SIZE); + if (!enc) + ksmbd_user_session_put(sess); return 0; } --- a/fs/smb/server/mgmt/user_session.c +++ b/fs/smb/server/mgmt/user_session.c @@ -180,7 +180,7 @@ static void ksmbd_expire_session(struct down_write(&sessions_table_lock); down_write(&conn->session_lock); xa_for_each(&conn->sessions, id, sess) { - if (atomic_read(&sess->refcnt) == 0 && + if (atomic_read(&sess->refcnt) <= 1 && (sess->state != SMB2_SESSION_VALID || time_after(jiffies, sess->last_active + SMB2_SESSION_TIMEOUT))) { @@ -232,7 +232,8 @@ void ksmbd_sessions_deregister(struct ks down_write(&conn->session_lock); xa_erase(&conn->sessions, sess->id); up_write(&conn->session_lock); - ksmbd_session_destroy(sess); + if (atomic_dec_and_test(&sess->refcnt)) + ksmbd_session_destroy(sess); } } } @@ -251,7 +252,8 @@ void ksmbd_sessions_deregister(struct ks if (xa_empty(&sess->ksmbd_chann_list)) { xa_erase(&conn->sessions, sess->id); hash_del(&sess->hlist); - ksmbd_session_destroy(sess); + if (atomic_dec_and_test(&sess->refcnt)) + ksmbd_session_destroy(sess); } } up_write(&conn->session_lock); @@ -327,8 +329,8 @@ void ksmbd_user_session_put(struct ksmbd if (atomic_read(&sess->refcnt) <= 0) WARN_ON(1); - else - atomic_dec(&sess->refcnt); + else if (atomic_dec_and_test(&sess->refcnt)) + ksmbd_session_destroy(sess); } struct preauth_session *ksmbd_preauth_session_alloc(struct ksmbd_conn *conn, @@ -399,7 +401,7 @@ static struct ksmbd_session *__session_c xa_init(&sess->rpc_handle_list); sess->sequence_number = 1; rwlock_init(&sess->tree_conns_lock); - atomic_set(&sess->refcnt, 1); + atomic_set(&sess->refcnt, 2); ret = __init_smb2_session(sess); if (ret) --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -2242,13 +2242,14 @@ int smb2_session_logoff(struct ksmbd_wor return -ENOENT; } - ksmbd_destroy_file_table(&sess->file_table); down_write(&conn->session_lock); sess->state = SMB2_SESSION_EXPIRED; up_write(&conn->session_lock); - ksmbd_free_user(sess->user); - sess->user = NULL; + if (sess->user) { + ksmbd_free_user(sess->user); + sess->user = NULL; + } ksmbd_all_conn_set_status(sess_id, KSMBD_SESS_NEED_NEGOTIATE); rsp->StructureSize = cpu_to_le16(4);