From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qt1-f198.google.com (mail-qt1-f198.google.com [209.85.160.198]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EDADB4FD279 for ; Mon, 21 Sep 2026 18:38:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.198 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790015884; cv=none; b=n+fPa8azhbmbGLLvzKN03Za4RuHA9KZtDmxfxa5BZOEoKAkUJgDSo8TI+0dHylqCIQ9rcXlq7U4kpX/CZX4uvjx9IqcohHTczNOezIWGxwPy2KktahMwcYK+fDKOYCe6FsU4jHiU7zfr3ir0erLfREOu/0jpw7H8reTkCZAaQuw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790015884; c=relaxed/simple; bh=JWXnG65qDAR3nc2NNQVBHHZqC5ePa0NnANIiel3wC1c=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=Ysthb28O0kY6MASOjruL8nCkpCK3E1Q0P6idIhSS76eQ0vBhTbVTk3VmRGp+bZflErnrTl+OEz7jS0Fk4jrTl5g+XYCLIeQ4q1mpKSZekTVlMpPj4uy4d58AUg4pw8fuP1KVlDqncDa7sDBBxG5eGF7E2wVHQLo9qXtYkq5mG7E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--edumazet.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=Z5Tzc/vJ; arc=none smtp.client-ip=209.85.160.198 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--edumazet.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Z5Tzc/vJ" Received: by mail-qt1-f198.google.com with SMTP id d75a77b69052e-532abbd5a51so56311121cf.2 for ; Mon, 21 Sep 2026 11:38:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1790015882; x=1790620682; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=/Gb6zRczsns+UrbrubIMKN7GDeRyCTA3JBV/2d9OGcs=; b=Z5Tzc/vJYLwvGy0QiA0N7RaIjSg3A6cO1LiydNG4m3I2COyIjzcQGwF38mIvx5zYnC fVF/OKGmLsczOyzZ46jIPaByO0nmkDwCVBaBECyfIuirH23zgy8tVc+2ae5hz15Yp0Wp 1JniPu8QLzfX/hcjKkha6W5YVTl5EmDqZkYxFRXL7ZYX2g4dciJfaodKAWOjrxiNygpz DdsiDrfLaAqxm6DYlGosYEUVzYlL4m0SZ/Xvvm+haMXZ3ypU06Kcl/K3+v4HFswmL3ZH WGlqb0cqZ9XxWmpsJhaHvmHVTQ1BxCl/jPEqPfYbCRyxE949teefCLxUvC9lB6Zx+MQZ O6XA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790015882; x=1790620682; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=/Gb6zRczsns+UrbrubIMKN7GDeRyCTA3JBV/2d9OGcs=; b=d205QGclTymyP8PtZ+lyQRo7Sx8Udm95EFYT4J7xrLzXPuL4l/hKo5qXBbRzbisKMz +U29qatf70jmS62wBxURy7wBszP4Fc/kp6nLvtssk2phfvjI1P5JEVE0BzDj26cAthDf eqcsQGNS2s+hecbAqhKDskthHPebSO8o7G8zKPLfZ2Dtblt5W5EE702eUUazI2Kl0kyw csSwYxNfhT5YXOD+B05rrQSYPKao+ukCGFt41uPsMoEsWGHZBQ/OmhSdVMjfAj+ICz34 8lhqyd2Z+k+jzWdwF73Qj7FdNbNpjllVoBbPsedHal/biHf6FNVkEnIeVELqR7UUNZnL kvCA== X-Forwarded-Encrypted: i=1; AKwUvBysMzkOSyXVl0RsR2CnntalLJy7fxDQFhXGRmf8sHRtr5G6opZHIJItqBbK5H4WvlLydpauko0=@vger.kernel.org X-Gm-Message-State: AFuF++n6GLvk+cOGciZzUo6xzr4hzCIOFbjmEMU8glblKlGtXezYgvjx LrpWRh1lk5AtpBaVqZJy0xADN4cEmQOReL4KHZZZVJ9kt9/1mIFdtP/hPrMz06XC9LWJREZvsu8 yfBc+mlN6+wY/Ug== X-Received: from qtbdq9.prod.google.com ([2002:a05:622a:5209:b0:530:dad9:746f]) (user=edumazet job=prod-delivery.src-stubby-dispatcher) by 2002:a05:622a:558a:b0:530:41f5:f695 with SMTP id d75a77b69052e-532d8e0cc20mr17417211cf.32.1790015881586; Mon, 21 Sep 2026 11:38:01 -0700 (PDT) Date: Mon, 21 Sep 2026 18:37:54 +0000 In-Reply-To: <20260921183758.1812310-1-edumazet@google.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260921183758.1812310-1-edumazet@google.com> X-Mailer: git-send-email 2.55.0.1082.g2b9226bbc0-goog Message-ID: <20260921183758.1812310-2-edumazet@google.com> Subject: [PATCH net-next 1/5] net: synchronize proc_do_rss_key() with netdev_rss_key_fill() From: Eric Dumazet To: "David S . Miller" , Jakub Kicinski , Paolo Abeni Cc: Willem de Bruijn , Simon Horman , netdev@vger.kernel.org, eric.dumazet@gmail.com, Eric Dumazet Content-Type: text/plain; charset="UTF-8" proc_do_rss_key() reads netdev_rss_key[] without synchronization, so a concurrent reader of /proc/sys/net/core/netdev_rss_key can observe a partially populated key while netdev_rss_key_fill() is initializing it. Publish a boolean flag after an smp_wmb() once netdev_rss_key_fill() has populated netdev_rss_key[], and pair it with an smp_rmb() in proc_do_rss_key(), printing zero bytes until the flag is set. Fixes: 960fb622f851 ("net: provide a per host RSS key generic infrastructure") Signed-off-by: Eric Dumazet --- net/core/dev.h | 1 + net/core/sysctl_net_core.c | 7 ++++++- net/ethtool/ioctl.c | 7 +++++++ 3 files changed, 14 insertions(+), 1 deletion(-) diff --git a/net/core/dev.h b/net/core/dev.h index b757faead4d1a3e445e54d2f468c38c9e09b6762..0127b4d03e5251e0ad695aa649d0c52c2248bc8c 100644 --- a/net/core/dev.h +++ b/net/core/dev.h @@ -95,6 +95,7 @@ extern int netdev_unregister_timeout_secs; extern int weight_p; extern int dev_weight_rx_bias; extern int dev_weight_tx_bias; +extern bool netdev_rss_key_initialized; extern struct rw_semaphore dev_addr_sem; diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c index 23310581f494553e3ad8c4e010c7799e04f976c0..e30219765db3991f46fdcb96236e7eaf0878a0cc 100644 --- a/net/core/sysctl_net_core.c +++ b/net/core/sysctl_net_core.c @@ -338,9 +338,14 @@ static int proc_do_rss_key(const struct ctl_table *table, int write, char buf[NETDEV_RSS_KEY_LEN * 3]; struct ctl_table fake_table; char *pos = buf; + bool initialized; + + initialized = READ_ONCE(netdev_rss_key_initialized); + /* Pair with smp_wmb() in netdev_rss_key_fill(). */ + smp_rmb(); for (int i = 0; i < NETDEV_RSS_KEY_LEN; i++) { - pos = hex_byte_pack(pos, netdev_rss_key[i]); + pos = hex_byte_pack(pos, initialized ? netdev_rss_key[i] : 0); *pos++ = ':'; } *(--pos) = 0; diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c index 4b0bc503f9307880e436d5ee30f75476264a0c6b..b2820f02ca2790a8a3c13395e20040ee6976006f 100644 --- a/net/ethtool/ioctl.c +++ b/net/ethtool/ioctl.c @@ -34,6 +34,7 @@ #include #include +#include "../core/dev.h" #include "common.h" /* State held across locks and calls for commands which have devlink fallback */ @@ -1302,11 +1303,17 @@ static int ethtool_copy_validate_indir(u32 *indir, void __user *useraddr, } u8 netdev_rss_key[NETDEV_RSS_KEY_LEN] __read_mostly; +bool netdev_rss_key_initialized __read_mostly; void netdev_rss_key_fill(void *buffer, size_t len) { BUG_ON(len > sizeof(netdev_rss_key)); net_get_random_once(netdev_rss_key, sizeof(netdev_rss_key)); + if (unlikely(!READ_ONCE(netdev_rss_key_initialized))) { + /* Pair with smp_rmb() in proc_do_rss_key(). */ + smp_wmb(); + WRITE_ONCE(netdev_rss_key_initialized, true); + } memcpy(buffer, netdev_rss_key, len); } EXPORT_SYMBOL(netdev_rss_key_fill); -- 2.55.0.1082.g2b9226bbc0-goog