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 7E8373B38AE; Fri, 24 Apr 2026 13:42:15 +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=1777038135; cv=none; b=qGWTindZvlDCueaWFDhuZu26yebmb8DB+UjSwD80DvCBEOaDSf+ijVAhS280FBsMtkMRTB4OjSQ1SNGwofQjnliIa3sIR5PeMCoNbsJ6hEyxVuU6KEAUhZAla7clSoq6sBXybRZ5x/rjzGgYxwOrXSygAqSSR5ZhBrz1WYZ85Ag= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777038135; c=relaxed/simple; bh=6oelODnQ57yPEnb7Obj16DbQoIA1jaacm9PqupWX/z0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=c7hq1gR2ncmvxJcyibedNrbaghU0G0vP6iSzFz7WysQEkoHI547Uq3uhOdssnL9d7XARdYR9sRgT/3D6xRoSfrOwrVQgJ02yCsJalCi8u8qvJoIb8ouIfExZ/ng6exN1+ydNBxpgPkXunIJDdjym91W5zdOmHIccSndsRL3Q1sU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=TfXhxmSV; 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="TfXhxmSV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 130C5C19425; Fri, 24 Apr 2026 13:42:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1777038135; bh=6oelODnQ57yPEnb7Obj16DbQoIA1jaacm9PqupWX/z0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TfXhxmSVX3sJZJpmFe2wPxvnE4i692XENsze3p4JDxMR/4hpWo5ocI5VAvHP5dje0 ApLPjrqDDNV5HZ5aDhuuUhiXGFlMsnuM996GiE7ywRx/vbRnWSiQbpdigdALAtb6W6 jUPpZUjigD8sMFCyEhnEQj1PUuPLTUSUMCNSBQX0= 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 6.18 38/55] smb: server: fix max_connections off-by-one in tcp accept path Date: Fri, 24 Apr 2026 15:31:17 +0200 Message-ID: <20260424132437.910251615@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: 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 @@ -301,7 +301,7 @@ 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);