From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yx1-f49.google.com (mail-yx1-f49.google.com [74.125.224.49]) (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 C1F6147D941 for ; Wed, 1 Apr 2026 17:33:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.224.49 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775064816; cv=none; b=HFub0L6n3+iTXSY0YvOF2FR7Zggpk6g/lDHwSM5x9bfe8tq//1vtGnKoFJjHvY+FA1BjIvvvTK0cgcgWONDmSHRCQkDRv5BhV6csPvD+ED1MMsk1P/FPTIsxen9G1GLErGHnHqOSvdlHK+SpPufIleCFfUIozFMgO/E2JWEDofo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775064816; c=relaxed/simple; bh=GALUpL9FcmSNoTtHE6SpePyLmLDTRd/mTbP3SWjUuZY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=UBfXcZ0UdXVi5Aj+T+AYZc6t0+wHK1jZW4iZcQ1hZGl9f37iI2Na3/MV5P0CIHjGlh0s8MIiDsFFTUXtPUxBG+CVH9z+C081qdqJdq0feSMTaOSofKHgyoIcG14T0Iz9aip9mGogPBWtBS0iLaqZ+oJljsvi7nGGlMr+LFOeYMI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=s1Iz1jDZ; arc=none smtp.client-ip=74.125.224.49 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="s1Iz1jDZ" Received: by mail-yx1-f49.google.com with SMTP id 956f58d0204a3-65032e9cf01so610d50.3 for ; Wed, 01 Apr 2026 10:33:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1775064814; x=1775669614; darn=lists.linux.dev; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=aLnfQJSw9REm8a9+311bKseMryW3/suAyHmSGj3g0SU=; b=s1Iz1jDZkAbEVIatKSbyV81ohrM+aVIowXOPLJkJnl597hGESjsqKL9/UnnIfhNZBH ny/AKzy1D1ed/a7e4kUbLR+eTOPOQ/5XUvpQu62jlSgAK2j/jRYt5fej/Qy2iKVZ7pUf 2CPE2BG5+ysrwwkR05rATXowjw/V8nsBM8pihU6Kmdkzzs7Uju/CKomwQ9mUkWI1ALjq fF49iM5mP2Ar7Vfqde+KUV1/2e5zmnQd2ZcCPOuSxG5hV1XnwjX140cbgziChgQjNvX2 C4tCaZrsqZU7GqVVDOYZHiMpBdrtZnbPkLWQcFrMTGQMIJ6TADOEmvBm9dSodpdlsEQ8 dUeA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1775064814; x=1775669614; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=aLnfQJSw9REm8a9+311bKseMryW3/suAyHmSGj3g0SU=; b=b/tYW2YrgVDGKoqRAvQ8aNGfgCOAgdSoaPQ7KouiKx3E5/gUZ8Q3StGrhKu1dIX+4B DhH5Gc0W5PxUSGJD+6mgCsr7baVIzM/Zu4ja6wpQwz0gIpcwo2j+Ijsf81lK8h9DgwBG jU61UlxGhxOx5rED1VR1y0dn+tMGqqfRZRJwJ/Tj2eoUtUormVzYAUuFt0omq3fzjlwg PRGZ69NfihDIEKKGggTgiEZQsDXwlzQzJ4Bqw/LcMrLhY6324S0lxkQwwdSNVMJ7Zu6T gZ5PTnv5NtSWiSdHpInOzq8O32M+bLsVY/A684UdiS0rQBbZ1uMDxRT9X5+1UbztuUNM 81AQ== X-Forwarded-Encrypted: i=1; AJvYcCW0wCilt+z0K+QwACh7zC5v8cJ2g1KgqQnpFci7jdvIfSK8TmAls7VWd6C739hFR5nRblsR9DdT3yfth26DCA==@lists.linux.dev X-Gm-Message-State: AOJu0YxR//Yofxwq33v4pYmOEDqA/3Z8kRwFOXqmdLwrizovpOh/B3pt cLOmKnXsk8AZzztjZrFyHrKm5PrxhMDc05I9yYStlB4w4h1DXhBBS4tf X-Gm-Gg: ATEYQzxqptLYGKh6jxKEh9VfOZtlq07GF1npjxq9WFyxDx6A5Aq8NRUDV/GW3UmykJu 5oNUOp+6MUs2t9yD49jS3x3GeHuGURhJqZ6O10gMhSPa290gGnwHzEz+6EZrcaZ9T4Z82iy9aei wDmYdydoVlCyToI30XPMHLpibzlzICF41s9/TR/4e686z1IIq6WGV3oblRE6gTrT2qMBFRfedhT 5lZ/j+wlamtDeWycSvhDcWNaVBBi2SYTLZyoQbdbmwDVNafahE8nD+7myXkqVGwRduqWUvU1Mb6 TJNyEyBQ6U+YbEiyKQfEzfos+OArQAJzjwZ5K5rvXs1Mymzm0FK1OMIJOUApnbW3cnKrrdYoHL8 2jnZKn1bn00t8zxfBNABXunK2xPq0ZEWh+dlEqUPRQ4KHOYrWoMXlNCHOsipB9YL6JF7q5Paf2C 1sxCaVKXdUdjYCrWbSuPraRvPWt4kkZYbv X-Received: by 2002:a05:690e:1c20:b0:650:3aae:e2e6 with SMTP id 956f58d0204a3-6503aaee65fmr764874d50.20.1775064813767; Wed, 01 Apr 2026 10:33:33 -0700 (PDT) Received: from syzkaller ([2a03:2880:25ff:5c::]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-6503a828f3csm214698d50.3.2026.04.01.10.33.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Apr 2026 10:33:32 -0700 (PDT) Date: Wed, 1 Apr 2026 10:33:27 -0700 From: Bobby Eshleman To: Stefano Garzarella Cc: netdev@vger.kernel.org, "David S. Miller" , linux-kernel@vger.kernel.org, Bobby Eshleman , Jakub Kicinski , Simon Horman , virtualization@lists.linux.dev, Eric Dumazet , Paolo Abeni , Jin Liu Subject: Re: [PATCH net] vsock: initialize child_ns_mode_locked in vsock_net_init() Message-ID: References: <20260401092153.28462-1-sgarzare@redhat.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260401092153.28462-1-sgarzare@redhat.com> On Wed, Apr 01, 2026 at 11:21:53AM +0200, Stefano Garzarella wrote: > From: Stefano Garzarella > > The `child_ns_mode_locked` field lives in `struct net`, which persists > across vsock module reloads. When the module is unloaded and reloaded, > `vsock_net_init()` resets `mode` and `child_ns_mode` back to their > default values, but does not reset `child_ns_mode_locked`. > > The stale lock from the previous module load causes subsequent writes > to `child_ns_mode` to silently fail: `vsock_net_set_child_mode()` sees > the old lock, skips updating the actual value, and returns success > when the requested mode matches the stale lock. The sysctl handler > reports no error, but `child_ns_mode` remains unchanged. > > Steps to reproduce: > $ modprobe vsock > $ echo local > /proc/sys/net/vsock/child_ns_mode > $ cat /proc/sys/net/vsock/child_ns_mode > local > $ modprobe -r vsock > $ modprobe vsock > $ echo local > /proc/sys/net/vsock/child_ns_mode > $ cat /proc/sys/net/vsock/child_ns_mode > global <--- expected "local" > > Fix this by initializing `child_ns_mode_locked` to 0 (unlocked) in > `vsock_net_init()`, so the write-once mechanism works correctly after > module reload. > > Fixes: 102eab95f025 ("vsock: lock down child_ns_mode as write-once") > Cc: bobbyeshleman@meta.com > Reported-by: Jin Liu > Signed-off-by: Stefano Garzarella > --- > net/vmw_vsock/af_vsock.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c > index 2f7d94d682cb..d912ed2f012a 100644 > --- a/net/vmw_vsock/af_vsock.c > +++ b/net/vmw_vsock/af_vsock.c > @@ -2928,6 +2928,7 @@ static void vsock_net_init(struct net *net) > net->vsock.mode = vsock_net_child_mode(current->nsproxy->net_ns); > > net->vsock.child_ns_mode = net->vsock.mode; > + net->vsock.child_ns_mode_locked = 0; > } > > static __net_init int vsock_sysctl_init_net(struct net *net) > -- > 2.53.0 > Reviewed-by: Bobby Eshleman