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 9691719E997; Thu, 6 Feb 2025 18:29:37 +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=1738866577; cv=none; b=eh0oOlUoLIuqkEj28NG6l4248UMN/fvZ7GN7O0qkUVvuXpImpIws02OSuHm2Z1LcvvWo4iCNEM3Bm9Ab6RjR2LtzTRJZnI26IQuwnTKZ6hp1qzelIJQxhWHAwGGWvq7uJ/Yx8gfsv3u7qUM/uKrjczG6x981vTxQARb4AAsZtqE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738866577; c=relaxed/simple; bh=bqkqVppprwv2/h3KLXNq5+ns9QVFkuJKls2nqG7a6IQ=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=o9KERw+oj4RFQ9lWxqEL+WvLlsvH58yD82S4F8vicbJmHFtbRpiVIVhES+2vF+v5Iu4Fj7ASuBdTc6TGeDrTpNRM3aEezXz9yLss6dXlPe3BfS6GzflG2FWBNhK3Ftiv2Upq3iY7PlU4Vsvoqw1/CSFBjLO0KvPaNHNjHns6DhM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lFRoFZqI; 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="lFRoFZqI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F2AF6C4CEE9; Thu, 6 Feb 2025 18:29:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1738866576; bh=bqkqVppprwv2/h3KLXNq5+ns9QVFkuJKls2nqG7a6IQ=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=lFRoFZqIH7TfivJ41MygpaJPk5W6OFt6IxlEDdaeeV5GQ456DYZ9BEJCMGHC6PXtM kQvILYiJDFPzdsxws1tnFQaMxBFzC9wBGtmQHRy28llvoJ7GJy8YMiKvttEQIPKkoZ 5c8rh64nFbm2zdeNEu8PB5TSrLrWsIZhaabpRqI+NmNoXgSMi4Y4I5eZZXX+cxBTlM Y0NKePEK0JIACInkHU6Yj7Piail8hWKuuB4yJm8QsNjJCn38lhWFPyT9jt3F9KpzHx M37cgaVDGmOL6JRMeS3mUwR3FhK2f4c70Nj9RCBqUW/rdzaG5dTd0Ji0GpWifsxepU G4hjL2MKJUUNQ== Message-ID: <232559042f0d52a858d02273a047a52282597d6b.camel@kernel.org> Subject: Re: [PATCH] nfsd: don't ignore the return code of svc_proc_register() From: Jeff Layton To: Chuck Lever , Neil Brown , Olga Kornievskaia , Dai Ngo , Tom Talpey , Josef Bacik Cc: linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+e34ad04f27991521104c@syzkaller.appspotmail.com Date: Thu, 06 Feb 2025 13:29:34 -0500 In-Reply-To: References: <20250206-nfsd-fixes-v1-1-c6647b92ca6f@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Thu, 2025-02-06 at 13:17 -0500, Chuck Lever wrote: > On 2/6/25 1:12 PM, Jeff Layton wrote: > > Currently, nfsd_proc_stat_init() ignores the return value of > > svc_proc_register(). If the procfile creation fails, then the kernel > > will WARN when it tries to remove the entry later. > >=20 > > Fix nfsd_proc_stat_init() to return the same type of pointer as > > svc_proc_register(), and fix up nfsd_net_init() to check that and fail > > the nfsd_net construction if it occurs. > >=20 > > svc_proc_register() can fail if the dentry can't be allocated, or if an > > identical dentry already exists. The second case is pretty unlikely in > > the nfsd_net construction codepath, so if this happens, return -ENOMEM. > >=20 > > Fixes: 93483ac5fec6 ("nfsd: expose /proc/net/sunrpc/nfsd in net namespa= ces") > > Reported-by: syzbot+e34ad04f27991521104c@syzkaller.appspotmail.com > > Closes: https://lore.kernel.org/linux-nfs/67a47501.050a0220.19061f.05f9= .GAE@google.com/ > > Signed-off-by: Jeff Layton > > --- > > I looked at the console log from the report, and syzkaller is doing > > fault injection on allocations. You can see the stack where the "nfsd" > > directory under /proc failed to be created due to one. This is a pretty > > unlikely bug under normal circumstances, but it's simple to fix. The > > problem predates the patch in Fixes:, but it's not worth the effort to > > backport this to anything earlier. >=20 > I'd prefer to document this by labeling the actual commit that > introduced the problem in the Fixes: tag, then using >=20 > "Cc: stable # vN.M" >=20 > to block automatic backporting to LTS kernels where this patch won't > apply cleanly. I can derive the values of N and M from the commit you > mention above, but do you happen to know the actual culprit commit? >=20 >=20 Unfortunately this bug goes back to the initial 2.6.12 import into git. I didn't look earlier.=C2=A0Note that nfsd is not alone here. Ignoring the result of proc_create_data() is very common. If you want to drop the Fixes: tag, and add the Cc: stable instead, then that's fine with me. Whatever works best. > > --- > > fs/nfsd/nfsctl.c | 9 ++++++++- > > fs/nfsd/stats.c | 4 ++-- > > fs/nfsd/stats.h | 2 +- > > 3 files changed, 11 insertions(+), 4 deletions(-) > >=20 > > diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c > > index 95ea4393305bd38493b640fbaba2e8f57f5a501d..583eda0df54dca394de4bbe= 8d148be2892df39cb 100644 > > --- a/fs/nfsd/nfsctl.c > > +++ b/fs/nfsd/nfsctl.c > > @@ -2204,8 +2204,14 @@ static __net_init int nfsd_net_init(struct net *= net) > > NFSD_STATS_COUNTERS_NUM); > > if (retval) > > goto out_repcache_error; > > + > > memset(&nn->nfsd_svcstats, 0, sizeof(nn->nfsd_svcstats)); > > nn->nfsd_svcstats.program =3D &nfsd_programs[0]; > > + if (!nfsd_proc_stat_init(net)) { > > + retval =3D -ENOMEM; > > + goto out_proc_error; > > + } > > + > > for (i =3D 0; i < sizeof(nn->nfsd_versions); i++) > > nn->nfsd_versions[i] =3D nfsd_support_version(i); > > for (i =3D 0; i < sizeof(nn->nfsd4_minorversions); i++) > > @@ -2215,12 +2221,13 @@ static __net_init int nfsd_net_init(struct net = *net) > > nfsd4_init_leases_net(nn); > > get_random_bytes(&nn->siphash_key, sizeof(nn->siphash_key)); > > seqlock_init(&nn->writeverf_lock); > > - nfsd_proc_stat_init(net); > > #if IS_ENABLED(CONFIG_NFS_LOCALIO) > > INIT_LIST_HEAD(&nn->local_clients); > > #endif > > return 0; > > =20 > > +out_proc_error: > > + percpu_counter_destroy_many(nn->counter, NFSD_STATS_COUNTERS_NUM); > > out_repcache_error: > > nfsd_idmap_shutdown(net); > > out_idmap_error: > > diff --git a/fs/nfsd/stats.c b/fs/nfsd/stats.c > > index bb22893f1157e4c159e123b6d8e25b8eab52e187..f7eaf95e20fc8758566f469= c6c2de79119fea070 100644 > > --- a/fs/nfsd/stats.c > > +++ b/fs/nfsd/stats.c > > @@ -73,11 +73,11 @@ static int nfsd_show(struct seq_file *seq, void *v) > > =20 > > DEFINE_PROC_SHOW_ATTRIBUTE(nfsd); > > =20 > > -void nfsd_proc_stat_init(struct net *net) > > +struct proc_dir_entry *nfsd_proc_stat_init(struct net *net) > > { > > struct nfsd_net *nn =3D net_generic(net, nfsd_net_id); > > =20 > > - svc_proc_register(net, &nn->nfsd_svcstats, &nfsd_proc_ops); > > + return svc_proc_register(net, &nn->nfsd_svcstats, &nfsd_proc_ops); > > } > > =20 > > void nfsd_proc_stat_shutdown(struct net *net) > > diff --git a/fs/nfsd/stats.h b/fs/nfsd/stats.h > > index 04aacb6c36e2576ba231ee481e3a3e9e9f255a61..e4efb0e4e56d467c13eaa5a= 1dd312c85dadeb4b8 100644 > > --- a/fs/nfsd/stats.h > > +++ b/fs/nfsd/stats.h > > @@ -10,7 +10,7 @@ > > #include > > #include > > =20 > > -void nfsd_proc_stat_init(struct net *net); > > +struct proc_dir_entry *nfsd_proc_stat_init(struct net *net); > > void nfsd_proc_stat_shutdown(struct net *net); > > =20 > > static inline void nfsd_stats_rc_hits_inc(struct nfsd_net *nn) > >=20 > > --- > > base-commit: ebbdc9429c39336a406b191cfe84bca2c12c2f73 > > change-id: 20250206-nfsd-fixes-8e61bdf66347 > >=20 > > Best regards, >=20 >=20 --=20 Jeff Layton