From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 63E193B5E01 for ; Mon, 22 Jun 2026 14:01:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782136895; cv=none; b=bTywpQVnBUoN3iXylAV6ZsNFNdrOnXBroATqoNiU8HEYI4lKqXP7xr8DGuPOR+0hADHO+cWfqK+iNVQHqQoPT+eMkpawJH/8sjc+jd1KxlK9zRZ4opZtfEq+in2EVwPDhtYjLV/kB96ubl9nVBP6RpoMxlIGz8IarqypH1sQHaY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782136895; c=relaxed/simple; bh=qe3sLENGLFxfz3zd7WgcQ2TdgZV62RqnJP5EAExszyA=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=OyjAW1e3G0wM0Dz6xoRhrzqziZzRwxL8DaYeqUjUTM65YyIM+/i+1gYFauSDbfTOBDKu5FMAzvjpGB5MpX2i7olBN+MUzpb4pV6co6/8rb4J6NPNnczvrn5PlvDBFVnsfjw7N2mDmntRCkCS4y1+L7GUsp70wjfcdx0p9aTZszg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Q9E+wZZN; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Q9E+wZZN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5EBB71F000E9; Mon, 22 Jun 2026 14:01:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782136894; bh=qe3sLENGLFxfz3zd7WgcQ2TdgZV62RqnJP5EAExszyA=; h=Subject:From:To:Cc:Date:In-Reply-To:References; b=Q9E+wZZNpbIlgDARA2XcD47RCHcY/lBE/P+OLixVWuODw5u8gtO1e8a4BRaM/jGRG 4tke2O82sremMsm/sdKE+BT8G+ur8AgyrLc5jnW13P/CY0xXEvwdDsQvTqg66oltZZ fupdYG/gOCb5K+1+vI1/Ngixe/zK1aubdfx6zo0vNJ5txhkggSKjditQCbzhc2h0fp XIdqhyJRCRv02uNtEtQYzaZheRIhcIPJxdLeV85/AVwP9/I3x6Udjy00ueYF4r/xCO kP/dQAVX8RGG0lnYfGr+1kKvWrBu/FaxLsHnLT3xf1UF4ZQ9+A+pBi8dvZvU/whQuS DTH6gesK4+IcQ== Message-ID: <2888cb8f7cde2ed76d59a807b2668cf95f1166ff.camel@kernel.org> Subject: Re: [PATCH] NFSD: Guard admin state-revocation walks with NFSD_NET_UP From: Jeff Layton To: Chuck Lever , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey Cc: linux-nfs@vger.kernel.org, XIAO WU Date: Mon, 22 Jun 2026 10:01:31 -0400 In-Reply-To: <2b3f6886-86ca-4da3-b1df-a2bec0f93e5f@app.fastmail.com> References: <20260621162551.2469460-1-cel@kernel.org> <8369948d3e01471c64d37182ddc6a2f1cdb0c473.camel@kernel.org> <2b3f6886-86ca-4da3-b1df-a2bec0f93e5f@app.fastmail.com> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Mon, 2026-06-22 at 09:14 -0400, Chuck Lever wrote: > On Mon, 2026-06-22 at 07:57 -0400, Jeff Layton wrote: > > Can nn->nfsd_serv be non-NULL while the NFSv4 state tables are still > > NULL? > > ... > > Would checking nn->nfsd_net_up instead of nn->nfsd_serv be more > > accurate here, since nfsd_net_up is set at the tail of > > nfsd_startup_net() exactly when the state tables become valid? >=20 > Yep, that's exactly the gap. The hunk you've quoted is 1/3 of the > earlier "post-shutdown use-after-free" series, which only guarded the > shutdown side of the window. nn->nfsd_serv is also set at service > creation, before nfsd_startup_net() allocates conf_id_hashtbl, so the > startup side was still exposed. >=20 > The thread you're replying to is the follow-on that closes it: it > switches all three unlock paths (write_unlock_fs, > nfsd_nl_unlock_filesystem_doit, nfsd_nl_unlock_export_doit) from > nn->nfsd_serv to test_bit(NFSD_NET_UP, &nn->flags) and rewrites the > walkers' Context: notes to match. NFSD_NET_UP is set at the tail of > nfsd_startup_net() and cleared in nfsd_shutdown_net() after the tables > are freed, so it brackets precisely the window you describe. >=20 > I assume your comment was meant for 1/3 of that series rather than > this thread... but we've reached the same conclusion, so no action > needed beyond this patch, correct? Ahh right. I missed that that had been fixed in the other series. This is fine then. Reviewed-by: Jeff Layton