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 CFA032E2640; Wed, 18 Jun 2025 12:50:22 +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=1750251022; cv=none; b=TyexsjxpEtHVyd4eOsGfhUMX6nDrvxj/a37Td8fh4k/pWh0OG7F0yQdMhomQf2qbzcTKxNRfbJmsBZGhmJu6GvQ1QE6YgPBfT0S/rjAON0QmtaxZcVdJNyR8Slq4cYTAF6laKdh+d9sKDdYyEcxnG0q+tumafxLZv9T56wG/uww= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750251022; c=relaxed/simple; bh=RYR/2pZqj5WTEbQ5KPJo0gncf2BgYE0/xusGNgg2BA0=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=I0fXgC3AUhsrrBiHaYpVjMUFFRhD8hpgjPB7Rtd8wBGAjAISyzGkkCmKl0tTg129cS6Q5wQxzty0aYhTAbtvQa02WPQsIpXPM7+zcYrdndFvWExGAPCzRvkspg0mkwmg4LnECjB9nuu1BDWaf+w88t1i39yyZ/sz2tLKt7xnTHg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BQ0NfVCD; 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="BQ0NfVCD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 541C8C4CEE7; Wed, 18 Jun 2025 12:50:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1750251022; bh=RYR/2pZqj5WTEbQ5KPJo0gncf2BgYE0/xusGNgg2BA0=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=BQ0NfVCDVnRFQhsGtrFT6kpDonnje10TRf58kL8JxTGk4OYfilvIMyh8ePtVZwznL 0VsPBuifWImFMAZhK+thXp8ZKJBUvq6dxjLE8uCcR4fsy/MJgWAoPObm5z0FiGyDeK 55wvl6fM9C9ugsoQQC8Fb8N6+Zbez134gL0oh71KzU2mlGMkootkep7cSydmLXLwZO c+nmgbFiWNE+xMQynbcIL23tbZ7x2P1hcEGOt0b8Qnk3xtUR4dbshxM6LhdPtHWsSO TPs5SBJl7QpTXo/XuC+7dsvm38PdrqkkgedmHG8lu0uDFY6CwPTK8y2t8HiQofoH0b 5owDWi+p31qmw== Message-ID: Subject: Re: [PATCH v2] nfsd: Invoke tracking callbacks only after initialization is complete From: Jeff Layton To: Li Lingfeng , chuck.lever@oracle.com, neilb@suse.de, okorniev@redhat.com, Dai.Ngo@oracle.com, tom@talpey.com, linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Cc: yukuai1@huaweicloud.com, houtao1@huawei.com, yi.zhang@huawei.com, yangerkun@huawei.com, lilingfeng@huaweicloud.com Date: Wed, 18 Jun 2025 08:50:20 -0400 In-Reply-To: <7bf3512276b6d314cbd9d250e16d617d41f3fa61.camel@kernel.org> References: <20250612035506.3651985-1-lilingfeng3@huawei.com> <7bf3512276b6d314cbd9d250e16d617d41f3fa61.camel@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw 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Evolution 3.56.2 (3.56.2-1.fc42) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, 2025-06-18 at 08:35 -0400, Jeff Layton wrote: > On Thu, 2025-06-12 at 11:55 +0800, Li Lingfeng wrote: > > Checking whether tracking callbacks can be called based on whether > > nn->client_tracking_ops is NULL may lead to callbacks being invoked > > before tracking initialization completes, causing resource access > > violations (UAF, NULL pointer dereference). Examples: > >=20 > > 1) nfsd4_client_tracking_init > > // set nn->client_tracking_ops > > nfsd4_cld_tracking_init > > nfs4_cld_state_init > > nn->reclaim_str_hashtbl =3D kmalloc_array > > ... // error path, goto err > > nfs4_cld_state_shutdown > > kfree(nn->reclaim_str_hashtbl) > > write_v4_end_grace > > nfsd4_end_grace > > nfsd4_record_grace_done > > nfsd4_cld_grace_done > > nfs4_release_reclaim > > nn->reclaim_str_hashtbl[i] > > // UAF > > // clear nn->client_tracking_ops > >=20 > > 2) nfsd4_client_tracking_init > > // set nn->client_tracking_ops > > nfsd4_cld_tracking_init > > write_v4_end_grace > > nfsd4_end_grace > > nfsd4_record_grace_done > > nfsd4_cld_grace_done > > alloc_cld_upcall > > cn =3D nn->cld_net > > spin_lock // cn->cn_lock > > // NULL deref > > // error path, skip init pipe > > __nfsd4_init_cld_pipe > > cn =3D kzalloc > > nn->cld_net =3D cn > > // clear nn->client_tracking_ops > >=20 >=20 >=20 > Have you seen this race in the wild? >=20 > Looking at this more closely, I don't think this race is possible. > You'd need to invoke the ->init routine concurrently from two different > tasks, but nfsd4_client_tracking_init is called during net ns > initialization, which should ensure that only one task invokes it. >=20 My bad. It's not called during net namespace initialization, but during server startup. But, the nfsd_mutex is held during this initialization, so I still don't think this race can happen. >=20 >=20 > > After nfsd mounts, users can trigger grace_done callbacks via > > /proc/fs/nfsd/v4_end_grace. If resources are uninitialized or freed > > in error paths, this causes access violations. > >=20 > > Resolve the issue by leveraging nfsd_mutex to prevent concurrency. > >=20 > > Fixes: 52e19c09a183 ("nfsd: make reclaim_str_hashtbl allocated per net"= ) > > Signed-off-by: Li Lingfeng > > --- > > Changes in v2: > > Use nfsd_mutex instead of adding a new flag to prevent concurrency. > > fs/nfsd/nfs4recover.c | 8 ++++++++ > > fs/nfsd/nfs4state.c | 4 ++++ > > fs/nfsd/nfsctl.c | 2 ++ > > 3 files changed, 14 insertions(+) > >=20 > > diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c > > index 82785db730d9..8ac089f8134c 100644 > > --- a/fs/nfsd/nfs4recover.c > > +++ b/fs/nfsd/nfs4recover.c > > @@ -162,7 +162,9 @@ legacy_recdir_name_error(struct nfs4_client *clp, i= nt error) > > if (error =3D=3D -ENOENT) { > > printk(KERN_ERR "NFSD: disabling legacy clientid tracking. " > > "Reboot recovery will not function correctly!\n"); > > + mutex_lock(&nfsd_mutex); > > nfsd4_client_tracking_exit(clp->net); > > + mutex_unlock(&nfsd_mutex); > > } > > } > > =20 > > @@ -2083,8 +2085,10 @@ nfsd4_client_record_create(struct nfs4_client *c= lp) > > { > > struct nfsd_net *nn =3D net_generic(clp->net, nfsd_net_id); > > =20 > > + mutex_lock(&nfsd_mutex); > > if (nn->client_tracking_ops) > > nn->client_tracking_ops->create(clp); > > + mutex_unlock(&nfsd_mutex); > > } > > =20 > > void > > @@ -2092,8 +2096,10 @@ nfsd4_client_record_remove(struct nfs4_client *c= lp) > > { > > struct nfsd_net *nn =3D net_generic(clp->net, nfsd_net_id); > > =20 > > + mutex_lock(&nfsd_mutex); > > if (nn->client_tracking_ops) > > nn->client_tracking_ops->remove(clp); > > + mutex_unlock(&nfsd_mutex); > > } > > =20 > > int > > @@ -2101,8 +2107,10 @@ nfsd4_client_record_check(struct nfs4_client *cl= p) > > { > > struct nfsd_net *nn =3D net_generic(clp->net, nfsd_net_id); > > =20 > > + mutex_lock(&nfsd_mutex); > > if (nn->client_tracking_ops) > > return nn->client_tracking_ops->check(clp); > > + mutex_unlock(&nfsd_mutex); > > =20 > > return -EOPNOTSUPP; > > } > > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > > index d5694987f86f..2794fdc8b678 100644 > > --- a/fs/nfsd/nfs4state.c > > +++ b/fs/nfsd/nfs4state.c > > @@ -2529,7 +2529,9 @@ static void inc_reclaim_complete(struct nfs4_clie= nt *clp) > > nn->reclaim_str_hashtbl_size) { > > printk(KERN_INFO "NFSD: all clients done reclaiming, ending NFSv4 gr= ace period (net %x)\n", > > clp->net->ns.inum); > > + mutex_lock(&nfsd_mutex); > > nfsd4_end_grace(nn); > > + mutex_unlock(&nfsd_mutex); > > } > > } > > =20 > > @@ -6773,7 +6775,9 @@ nfs4_laundromat(struct nfsd_net *nn) > > lt.new_timeo =3D 0; > > goto out; > > } > > + mutex_lock(&nfsd_mutex); > > nfsd4_end_grace(nn); > > + mutex_unlock(&nfsd_mutex); > > =20 > > spin_lock(&nn->s2s_cp_lock); > > idr_for_each_entry(&nn->s2s_cp_stateids, cps_t, i) { > > diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c > > index 3f3e9f6c4250..649850b4bb60 100644 > > --- a/fs/nfsd/nfsctl.c > > +++ b/fs/nfsd/nfsctl.c > > @@ -1085,7 +1085,9 @@ static ssize_t write_v4_end_grace(struct file *fi= le, char *buf, size_t size) > > if (!nn->nfsd_serv) > > return -EBUSY; > > trace_nfsd_end_grace(netns(file)); > > + mutex_lock(&nfsd_mutex); > > nfsd4_end_grace(nn); > > + mutex_lock(&nfsd_mutex); > > break; > > default: > > return -EINVAL; --=20 Jeff Layton