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 E562B3D75C3; Fri, 24 Apr 2026 13:43:55 +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=1777038236; cv=none; b=juOHlTp3m3nWlOzoQT3VI4PeI5Wr+StJk8OGHnPFObp7U1//KSW/sUHL09imMZkCTXSng6/azukOmBku8WjBol4w8STsV8/Bzq5g/qx3DeRNO35Rlqpgb6hMGWt7Yv/j6oB8qzyH+HZKHde8kQoUc71kJljiznHHs5ytyno3tBQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777038236; c=relaxed/simple; bh=95hERbtQx2TUw1WsmNf/wk5c1Qec9vQr86w67MxOIgw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=b/ktvEzChLKUrXlyJloSy7XCbGzwXzwUc0J+I1shVAOSjUtTk+RoU51VnT/jnXnsDmXUec7l6x5+y1x7jZCQFwua4Tatfw3iXyPMr94+29C/fijyNUf/ex/QCNmGXiMhz74zngr32oP+pfc4joHG+03pWPr4xFJDc1qWddGMGsc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=KZWgFXQn; 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="KZWgFXQn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7B342C19425; Fri, 24 Apr 2026 13:43:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1777038235; bh=95hERbtQx2TUw1WsmNf/wk5c1Qec9vQr86w67MxOIgw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KZWgFXQn7ZnPLpmLTMZN07WYnSTI6D2BqN0P2/pRXiiSI5Ck8M+OzYWTy521nOagZ +umnhdkbBv74VtYKss5tBezS/9hZg5ND2bHhRk1Ob/NSD83iI2PO8DWYggXtzDxck0 yLyyMHSVtD39vPXc4LLeD71t5zLm3jo1UfbB7VFY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, DaeMyung Kang , Namjae Jeon , Steve French Subject: [PATCH 6.12 21/35] smb: server: fix max_connections off-by-one in tcp accept path Date: Fri, 24 Apr 2026 15:31:28 +0200 Message-ID: <20260424132416.133584441@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260424132411.427029259@linuxfoundation.org> References: <20260424132411.427029259@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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: DaeMyung Kang commit ce23158bfe584bd90d1918f279fdf9de57802012 upstream. The global max_connections check in ksmbd's TCP accept path counts the newly accepted connection with atomic_inc_return(), but then rejects the connection when the result is greater than or equal to server_conf.max_connections. That makes the effective limit one smaller than configured. For example: - max_connections=1 rejects the first connection - max_connections=2 allows only one connection The per-IP limit in the same function uses <= correctly because it counts only pre-existing connections. The global limit instead checks the post-increment total, so it should reject only when that total exceeds the configured maximum. Fix this by changing the comparison from >= to >, so exactly max_connections simultaneous connections are allowed and the next one is rejected. This matches the documented meaning of max_connections in fs/smb/server/ksmbd_netlink.h as the "Number of maximum simultaneous connections". Fixes: 0d0d4680db22 ("ksmbd: add max connections parameter") Cc: stable@vger.kernel.org Signed-off-by: DaeMyung Kang Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman --- fs/smb/server/transport_tcp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/smb/server/transport_tcp.c +++ b/fs/smb/server/transport_tcp.c @@ -297,7 +297,7 @@ static int ksmbd_kthread_fn(void *p) skip_max_ip_conns_limit: if (server_conf.max_connections && - atomic_inc_return(&active_num_conn) >= server_conf.max_connections) { + atomic_inc_return(&active_num_conn) > server_conf.max_connections) { pr_info_ratelimited("Limit the maximum number of connections(%u)\n", atomic_read(&active_num_conn)); atomic_dec(&active_num_conn);