From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792586782; b=WlEFlKlVLeIdBFR9uamOQr1tQJbVj8nyw3oNTNySMW0YNy1ybQVPcsLXYeHSoGoTYdd2 CxHHNd1cfygtuQx1xgqFjPLKpAff+MEqIBWDFvkAWOKqjhBmd7foRXjykCQGTLvoLEfCs oQm3+YciU+j4GfXSxs3yVXjCTR6VLkfGoTix0MpdYnHTyqafA6UF/BfmXGGf3OJO73ftv XA5JsKK9kJz/aQj11y3Us1Iuc/A52jCJuf9LQus1H9pZeaEstCm0IJO89ZesM2T4Bufdb jLN2WlCNNAwJjW1n2YCedBiMgmDoyuywFbq+kNXn+0e+n3KikBsfC8CG+Frz6KMP15A== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792586782; h=Received:DKIM-Signature:Message-ID:Subject:From:To:Cc:Date: In-Reply-To:References:Autocrypt:Content-Type: Content-Transfer-Encoding:User-Agent:MIME-Version; bh=3HxypoKlJhiUOxRu9kwra01Pu+7Ut2AigS6g9BvU0a0=; b=oEn79OwYzBxQWbIYObx6ea3QS/a4lWJZam/16Wdhu+TfN7zVEAmrbH4rIhwwgQMQtUJf 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header.b=g9jMBe0y Received: by smtp.kernel.org (Postfix) with ESMTPSA id 26F8D1F000C4; Wed, 21 Oct 2026 12:46:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792586781; bh=3HxypoKlJhiUOxRu9kwra01Pu+7Ut2AigS6g9BvU0a0=; h=Subject:From:To:Cc:Date:In-Reply-To:References; b=g9jMBe0yU4yvG3TN2ACt4gljElfWu0P3rkwVrccOFOFuSoEtH/hBytjSiW/Kj917c D47Llr3X9zx77IxvKGb/C6FDIEFd7Lb/HopxDw6WzhuNVHr7bc8+VeBXYa1KdXzSk0 fZFLobQ40iH1fYMNhn+SOC+pOAzryFJWenmy+3vzexGrOvw9SciVTdbXy7Dmim2+BE IZWv9btR7ttank+7bgbLviNw7yd588M/5NB8CkNTV4T1jwNNXVJo+wI04o51aXUX4O 9bmulklnUAvwKBXcJZ6BtBS6W3zhBqHNMhdqonM8bVDRDQH9Q6ufSjF5vdYamX76hN SbRKWq9j9BLrQ== Message-ID: <8271fb05fba1237bd47cdeac967d8a9ec8f8abb9.camel@kernel.org> Subject: Re: [PATCH v3] nfsd: store net in svc_serv instead of deriving it from sv_permsocks From: Jeff Layton To: Deepanshu Kartikey , cel@kernel.org, neil@brown.name, okorniev@redhat.com, Dai.Ngo@oracle.com, tom@talpey.com, trondmy@kernel.org, anna@kernel.org, davem@davemloft.net, edumazet@kernel.org, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org Cc: bfields@fieldses.org, skinsbursky@parallels.com, linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, syzbot+561b859d032c8bf2fb53@syzkaller.appspotmail.com Date: Wed, 21 Oct 2026 08:46:18 -0400 In-Reply-To: <20261021124213.6288-1-kartikey406@gmail.com> References: <20261021124213.6288-1-kartikey406@gmail.com> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 0OX6MYPtv76hka8lW4mnRmZqqx3UtfHX/hF/zH24Gj7A6sYKYLCU3YrI2Ogiu7/ksKcl7goQjpvtV YrOOI5VGLHge0awt7bhMCTM9KAfPc+xL/ZxAMVWd3NCk5SamL2cE99UWgtvNOIYU8m6EjTLhsj8sn 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DfX/sn9XcfoVZIxMpCRE750zvJvcCUz9HojsrMQ1NFc7MFT1z3MOW2/RlzPcog7xvR5ENPH19ojRD CHqumUHRry+RF0lH00clzX/W8OrQJZtoBPXv9ahka/Vp7kEulcBJr1cH5Wz/WprhsIM7U9pse1f1g Yy9YbXtWctUz8uvDR7shsQxAhX3qO7DilMtuGo1v97I/Kx4gXQ52syh/w6EBny71CZrOgD6kJwPVV AaM1LRC28muq91WCFhs/nzHozpbzcheyGtMUI2Ao4K6mnY+3zIuXPygZMFr9KXE6fF7HzKxKuZMJO aEZCiDOq0anx6FmOzs5E6Jqdpo/mtI8beK+BE7Va6ni7YrQlnT0i3vaTVMTiCThbqsB20VrbMjlhp f8lfK1XVNbRq/R7GZ9zHESlsa35ha60yd/j3pu5hT2xyy8krV8vGhHvnJ1XRMJBAB/UYb6FyC7S+m QZIQXVeAA+smfTT0tDrisj1U5x6ZB9b3nBg65kc= Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.2 (3.60.2-2.fc44) X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 On Wed, 2026-10-21 at 18:12 +0530, Deepanshu Kartikey wrote: > nfsd() derives its struct net from the first entry of > serv->sv_permsocks using list_entry() without checking that the list > is non-empty. If the list is empty, list_entry() returns a bogus > svc_xprt computed from the list head embedded in struct svc_serv, and > the following perm_sock->xpt_net load reads past the end of the > svc_serv allocation: >=20 > BUG: KASAN: slab-out-of-bounds in nfsd+0x118/0xbc0 fs/nfsd/nfssvc.c:894 > Read of size 8 at addr ffff88802d423f50 by task nfsd/5988 >=20 > Rather than validating the list head before referencing it, store the > net in the svc_serv when it is created. svc_create_pooled() is only > used by nfsd, so add a struct net argument to it and record it in a > new sv_net field, then use that in nfsd(). >=20 > Fixes: 88c476661719 ("nfsd: pass proper net to nfsd_destroy() from NFSd k= threads") > Reported-by: syzbot+561b859d032c8bf2fb53@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=3D561b859d032c8bf2fb53 > Suggested-by: NeilBrown > Tested-by: syzbot+561b859d032c8bf2fb53@syzkaller.appspotmail.com > Reviewed-by: NeilBrown > Signed-off-by: Deepanshu Kartikey > --- > v3: reword commit message, fix stray whitespace in svc_create_pooled() > prototype (Neil) > v2: store the net in svc_serv via svc_create_pooled() instead of > walking sv_permsocks under sv_lock (Jeff, Neil) > --- > fs/nfsd/nfssvc.c | 5 ++--- > include/linux/sunrpc/svc.h | 2 ++ > net/sunrpc/svc.c | 3 +++ > 3 files changed, 7 insertions(+), 3 deletions(-) >=20 > diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c > index 2edf716ea022..06a756d5636c 100644 > --- a/fs/nfsd/nfssvc.c > +++ b/fs/nfsd/nfssvc.c > @@ -620,7 +620,7 @@ int nfsd_create_serv(struct net *net) > nfsd_max_blksize =3D nfsd_get_default_max_blksize(); > nfsd_reset_versions(nn); > serv =3D svc_create_pooled(nfsd_programs, ARRAY_SIZE(nfsd_programs), > - &nn->nfsd_svcstats, > + &nn->nfsd_svcstats, net, > nfsd_max_blksize, nfsd); > if (serv =3D=3D NULL) { > percpu_ref_exit(&nn->nfsd_net_ref); > @@ -890,8 +890,7 @@ nfsd(void *vrqstp) > { > struct svc_rqst *rqstp =3D (struct svc_rqst *) vrqstp; > struct svc_pool *pool =3D rqstp->rq_pool; > - struct svc_xprt *perm_sock =3D list_entry(rqstp->rq_server->sv_permsock= s.next, typeof(struct svc_xprt), xpt_list); > - struct net *net =3D perm_sock->xpt_net; > + struct net *net =3D rqstp->rq_server->sv_net; > struct nfsd_net *nn =3D net_generic(net, nfsd_net_id); > struct nfsd_thread_local_info ntli =3D { }; > bool have_mutex =3D false; > diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h > index 2db1b9ec5658..49a5052b2670 100644 > --- a/include/linux/sunrpc/svc.h > +++ b/include/linux/sunrpc/svc.h > @@ -72,6 +72,7 @@ enum { > struct svc_serv { > struct svc_program * sv_programs; /* RPC programs */ > struct svc_stat * sv_stats; /* RPC statistics */ > + struct net *sv_net; /* only set for pooled (nfsd) services */ > spinlock_t sv_lock; > unsigned int sv_nprogs; /* Number of sv_programs */ > unsigned int sv_nrthreads; /* # of running server threads */ > @@ -461,6 +462,7 @@ void svc_exit_thread(struct svc_rqst *); > struct svc_serv * svc_create_pooled(struct svc_program *prog, > unsigned int nprog, > struct svc_stat *stats, > + struct net *net, > unsigned int bufsize, > int (*threadfn)(void *data)); > int svc_set_pool_threads(struct svc_serv *serv, struct svc_pool *poo= l, > diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c > index 8297bad2b177..810c2db27fe3 100644 > --- a/net/sunrpc/svc.c > +++ b/net/sunrpc/svc.c > @@ -481,6 +481,7 @@ EXPORT_SYMBOL_GPL(svc_create); > * @prog: Array of RPC programs the new service will handle > * @nprogs: Number of programs in the array > * @stats: the stats struct if desired > + * @net: network namespace the service belongs to > * @bufsize: maximum message size for @prog > * @threadfn: a function to service RPC requests for @prog > * > @@ -489,6 +490,7 @@ EXPORT_SYMBOL_GPL(svc_create); > struct svc_serv *svc_create_pooled(struct svc_program *prog, > unsigned int nprogs, > struct svc_stat *stats, > + struct net *net, > unsigned int bufsize, > int (*threadfn)(void *data)) > { > @@ -502,6 +504,7 @@ struct svc_serv *svc_create_pooled(struct svc_program= *prog, > if (!serv) > goto out_err; > serv->sv_is_pooled =3D true; > + serv->sv_net =3D net; > return serv; > out_err: > svc_pool_map_put(); Much nicer. Reviewed-by: Jeff Layton