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 7DA3837F8A9; Tue, 5 May 2026 10:53:39 +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=1777978419; cv=none; b=FpukNLTZYnLiA83T+kGvWMidPRgWERpU2aqWzkliWbmjNSUQRhpZHjWDM8OaAJnoCOBAcbmVlQ9aN5wyEMnUOXYYlElqg3/D9i13skF2mN2q/ddbmC6X2BGkVAspOE7IKEcd+yzr2owC7VtAEsE6zxU2DnryJ0bigy/4wZ8ez0E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777978419; c=relaxed/simple; bh=KnbhoE0I3ur7S4TEiFuzxCqvEtZyRA7GqwIvsBNPZNY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=bIaRY2RwJAqDFlmZ0LIVOA1mP6QYsUsoQdQVgRvQ04QZkEZMGSDiqMG2C0LKw6rsGmqmLaEUiAHv/4d3jmfD+UzqzAO1tpUdqSqQokrO79rqe0tQrZ4lAGczSce0ox+nqueOjZcJ/InJ5MQyPuFlDA8nIACGosFUQYt1XZjPAjA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=s8vHvdRa; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="s8vHvdRa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3D83EC2BCB4; Tue, 5 May 2026 10:53:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777978419; bh=KnbhoE0I3ur7S4TEiFuzxCqvEtZyRA7GqwIvsBNPZNY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=s8vHvdRak07XxK44RE8ppW82HVQsCQKcP+fKBxBOr1EsyVdnhK6GSs8k/Y0PxWtZY F6lTsJPDCSvxl0nmZM6yCrSDgCFf5+/peU9RzxB8JF1FBqYHPTwoeOCqfWWYrkeiNA y0enlnuqWncFo4TSbyMuXIWGhU9LpujvxWIqVhvx+V3rse4PrcK/sO6Cx0Ai6Lu1a3 /lpewou5wRo7loNYjLa/sNUUQ15qX35aUjAg0LX9Utr5ujemSKuAG7SzMGLzkbopAr Y7AaYQOLdKQzkdlzmjQKWvgCJ1PdVwMdp0xp9B7Mci3gYOzgjT3/y7XJIOhUQLA90H wqQwSnlNBigOw== Message-ID: <8d3fbb91-65c4-4d15-ac38-3e6372eb0ffa@kernel.org> Date: Tue, 5 May 2026 12:53:32 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/6] SUNRPC: Address remaining cache_check_rcu() UAF in cache content files To: Calum Mackay , Misbah Anjum N , Jeff Layton , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey , Trond Myklebust , Anna Schumaker , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Yang Erkun Cc: linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Chuck Lever , alexandr.alexandrov@oracle.com References: <20260501-cache-uaf-fix-v1-0-a49928bf4817@oracle.com> From: Chuck Lever Content-Language: en-US Organization: kernel.org In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 5/5/26 12:49 PM, Calum Mackay wrote: > On 01/05/2026 3:51 pm, Chuck Lever wrote: >> Misbah Anjum reported a use-after-free in cache_check_rcu() >> reached through e_show() while sosreport was reading >> /proc/fs/nfsd/exports on ppc64le.  Two fixes for that report >> landed in v7.0: >> >>    48db892356d6 ("NFSD: Defer sub-object cleanup in export put >> callbacks") >>    e7fcf179b82d ("NFSD: Hold net reference for the lifetime of /proc/ >> fs/nfs/exports fd") >> >> The original e_show() repro is now fixed.  However, the same >> sosreport workload still reproduces a closely related fault on >> post-v7.0 mainline (Misbah, ppc64le) and on master.20260424 >> (internal report, aarch64).  In both cases the fault is in >> cache_check_rcu() reached through c_show() rather than e_show(), >> and the cache_head pointer is plain garbage: >> >>    pc : cache_check_rcu+0x40 [sunrpc] >>    lr : c_show+0x60 [sunrpc] >>    ...faulting on h->flags off h = 0x0000000200000000 >> >> c_show() is the generic show callback used by >> /proc/net/rpc//content for every per-net cache_detail >> (auth.unix.ip, auth.unix.gid, nfsd.fh, nfsd.export).  Two >> bugs combine in that path: >> >> 1. cache_unregister_net() / cache_destroy_net() free cd and >>     cd->hash_table synchronously when the namespace exits.  The >>     /proc/net/rpc/.../content open path takes only a module >>     reference, so a fd kept open across a netns exit walks a >>     freed hash_table and returns garbage cache_head pointers. >>     This is the same hazard that e7fcf179b82d closed for the >>     /proc/fs/nfs/exports file alone. >> >> 2. ip_map_put() drops auth_domain_put() before kfree_rcu(), so >>     sub-objects can be freed before the RCU grace period -- the >>     same hazard that 48db892356d6 fixed for svc_export_put() and >>     expkey_put().  unix_gid_put() does not have this bug >>     structurally (its put_group_info() runs inside the call_rcu() >>     callback) but it uses a separate idiom from the other three >>     caches. >> >> This series replaces the v1 narrow fixes with shared >> infrastructure that covers all four cache_detail .put paths >> and all three per-cache file types: >> >> Patch 1 hoists nfsd_export_wq up to the sunrpc layer as >> sunrpc_cache_wq, exposed through sunrpc_cache_queue_release() >> and sunrpc_cache_drain() so all four put callbacks share one >> workqueue and one drain primitive. >> >> Patch 2 converts ip_map_put() to the queue_rcu_work() pattern, >> moving auth_domain_put() into a deferred ip_map_release() that >> runs after the RCU grace period. >> >> Patch 3 unifies unix_gid_put() onto the same pattern for >> consistency (not a bug fix on its own). >> >> Patch 4 takes a get_net(cd->net) in content_open(), cache_open(), >> and open_flush() and drops it in the matching release helpers, >> so cache_destroy_net() cannot run while a sunrpc cache fd is >> open. >> >> Series has been compile-tested only. >> >> --- >> Chuck Lever (6): >>        SUNRPC: Move cache_initialize() declaration to sunrpc-private >> header >>        SUNRPC: Provide a shared workqueue for cache release callbacks >>        SUNRPC: Defer ip_map sub-object cleanup past RCU grace period >>        SUNRPC: Use shared release pattern for the unix_gid cache >>        SUNRPC: Hold cd->net for the lifetime of cache files >>        NFSD: Convert nfsd_export_shutdown() to sunrpc_cache_destroy_net() >> >>   fs/nfsd/export.c             | 45 ++-------------------- >>   fs/nfsd/export.h             |  2 - >>   fs/nfsd/nfsctl.c             |  8 +--- >>   include/linux/sunrpc/cache.h |  3 +- >>   net/sunrpc/cache.c           | 90 ++++++++++++++++++++++++++++++++++ >> ++++++++-- >>   net/sunrpc/sunrpc.h          |  2 + >>   net/sunrpc/sunrpc_syms.c     | 23 ++++++----- >>   net/sunrpc/svcauth_unix.c    | 46 ++++++++++++---------- >>   8 files changed, 135 insertions(+), 84 deletions(-) >> --- >> base-commit: f3a313ecd1fdab1f5da119db355363b13af6fcac >> change-id: 20260430-cache-uaf-fix-a13000f67c37 >> >> Best regards, >> -- >> Chuck Lever >> >> > > Looks good Chuck, thanks very much. > > With these patches, testing shows no crashes, sosreport no longer hangs, > no seq_file errors. > > Tested-by: Alexandr Alexandrov > > cheers, > c. > Excellent; pushed with Jeff's R-b and Alexandr's T-b. -- Chuck Lever