From nobody Sun Feb 8 11:21:48 2026 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 5206B33D6D1; Tue, 11 Nov 2025 21:29:58 +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=1762896599; cv=none; b=LmSoLQkaOoNz+2Yj90u730p41z3IljaPO8zLTmkZXy3eC6itbRMdCMlKhPB7vU7MCRCUjLrKvf9K60AigDc145zyy7qgBgt1KUFyHB6w2OzUdsOH00zF8nENvYCRh96ezVbathLKh9VX/bXInii19lUff+F7+8Shj1uGMR6yiis= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762896599; c=relaxed/simple; bh=/bC50lhCtcx6OG7oIZHLvFZOizTdGgNdqLCTc3tazgg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NQP8WoZOmI238qE13vbIgKwzS5UitDzRHGBkvd8s98EHtZERrK90nf+8mZZpT05uz4lGj9MUaauQW4fy+1UBPksuR5mK2K9HlWXowkSsHxyYFQgCtEzSLb+eDPkao6n7XXFsjcsCq7XGK5BLzGmANnHy5btieP+CwF4IKTJ1OXU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=uGKgOZih; 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="uGKgOZih" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4CBE2C116D0; Tue, 11 Nov 2025 21:29:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762896598; bh=/bC50lhCtcx6OG7oIZHLvFZOizTdGgNdqLCTc3tazgg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uGKgOZihX6WkxOXaYaMp7Ce45mAoZy1EdfFSGzxey8lL8ehrEFIL28KuIarmg/MNN q3HW4jyWthAJ8uUu/tNQsUJIcWjqrwAyZYS2WAzJFEVqjfCokNpJ+pA5pdwBRqWMey bPGuKEJQFW0OLIvy59Fzs8zpgRKcZmZjpPqjwd1hcYyG4KMM7du5CZ+tP62TLx16s2 vDik8OOPhpjo+w0OVb0HfR9Y1msHmcC+CUnE13AHRG//Nak7D47T7MeOw4cM6XUuLE SN+jmchssstwp47zqOcbrNN6mzaZpHQXpJoluWRAwVhesyL1Yvf7L+IGOI9KCkFGB8 ZB7mc1l3UU0Dw== From: Christian Brauner To: syzbot Cc: Christian Brauner , akpm@linux-foundation.org, bpf@vger.kernel.org, bsegall@google.com, david@redhat.com, dietmar.eggemann@arm.com, jack@suse.cz, jsavitz@redhat.com, juri.lelli@redhat.com, kartikey406@gmail.com, kees@kernel.org, liam.howlett@oracle.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-security-module@vger.kernel.org, lorenzo.stoakes@oracle.com, mgorman@suse.de, mhocko@suse.com, mingo@redhat.com, mjguzik@gmail.com, oleg@redhat.com, paul@paul-moore.com, peterz@infradead.org, rostedt@goodmis.org, rppt@kernel.org, sergeh@kernel.org, surenb@google.com, syzkaller-bugs@googlegroups.com, vbabka@suse.cz, vincent.guittot@linaro.org, viro@zeniv.linux.org.uk, vschneid@redhat.com, syzbot+0a8655a80e189278487e@syzkaller.appspotmail.com Subject: [PATCH] nsproxy: fix free_nsproxy() and simplify create_new_namespaces() Date: Tue, 11 Nov 2025 22:29:44 +0100 Message-ID: <20251111-sakralbau-guthaben-7dcc277d337f@brauner> X-Mailer: git-send-email 2.47.3 In-Reply-To: <691360cc.a70a0220.22f260.013e.GAE@google.com> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=6748; i=brauner@kernel.org; h=from:subject:message-id; bh=/bC50lhCtcx6OG7oIZHLvFZOizTdGgNdqLCTc3tazgg=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWQKrzr99kkW6wzH6+UP/PreNc3KE2rfU+NbHrZ+xbWOF t7s6PTXHaUsDGJcDLJiiiwO7Sbhcst5KjYbZWrAzGFlAhnCwMUpABPRDmVkuJPxT1/H9VJg0TpP bYu9tkz6hpfdpUT+6F3i3+xsae+1ieGv0BItmR8v/+iyT+J6VCyx5du09JVfWi1ua75+sX5Kp8w rHgA= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Make it possible to handle NULL being passed to the reference count helpers instead of forcing the caller to handle this. Afterwards we can nicely allow a cleanup guard to handle nsproxy freeing. Active reference count handling is not done in nsproxy_free() but rather in free_nsproxy() as nsproxy_free() is also called from setns() failure paths where a new nsproxy has been prepared but has not been marked as active via switch_task_namespaces(). Fixes: 3c9820d5c64a ("ns: add active reference count") Reported-by: syzbot+0b2e79f91ff6579bfa5b@syzkaller.appspotmail.com Reported-by: syzbot+0a8655a80e189278487e@syzkaller.appspotmail.com Link: https://lore.kernel.org/690bfb9e.050a0220.2e3c35.0013.GAE@google.com Signed-off-by: Christian Brauner Reviewed-by: Jan Kara --- include/linux/ns_common.h | 11 ++-- kernel/nsproxy.c | 107 +++++++++++++++----------------------- 2 files changed, 48 insertions(+), 70 deletions(-) diff --git a/include/linux/ns_common.h b/include/linux/ns_common.h index 136f6a322e53..825f5865bfc5 100644 --- a/include/linux/ns_common.h +++ b/include/linux/ns_common.h @@ -114,11 +114,14 @@ static __always_inline __must_check bool __ns_ref_dec= _and_lock(struct ns_common } =20 #define ns_ref_read(__ns) __ns_ref_read(to_ns_common((__ns))) -#define ns_ref_inc(__ns) __ns_ref_inc(to_ns_common((__ns))) -#define ns_ref_get(__ns) __ns_ref_get(to_ns_common((__ns))) -#define ns_ref_put(__ns) __ns_ref_put(to_ns_common((__ns))) +#define ns_ref_inc(__ns) \ + do { if (__ns) __ns_ref_inc(to_ns_common((__ns))); } while (0) +#define ns_ref_get(__ns) \ + ((__ns) ? __ns_ref_get(to_ns_common((__ns))) : false) +#define ns_ref_put(__ns) \ + ((__ns) ? __ns_ref_put(to_ns_common((__ns))) : false) #define ns_ref_put_and_lock(__ns, __ns_lock) \ - __ns_ref_dec_and_lock(to_ns_common((__ns)), __ns_lock) + ((__ns) ? __ns_ref_dec_and_lock(to_ns_common((__ns)), __ns_lock) : false) =20 #define ns_ref_active_read(__ns) \ ((__ns) ? __ns_ref_active_read(to_ns_common(__ns)) : 0) diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c index 94c2cfe0afa1..2c94452dc793 100644 --- a/kernel/nsproxy.c +++ b/kernel/nsproxy.c @@ -60,6 +60,27 @@ static inline struct nsproxy *create_nsproxy(void) return nsproxy; } =20 +static inline void nsproxy_free(struct nsproxy *ns) +{ + put_mnt_ns(ns->mnt_ns); + put_uts_ns(ns->uts_ns); + put_ipc_ns(ns->ipc_ns); + put_pid_ns(ns->pid_ns_for_children); + put_time_ns(ns->time_ns); + put_time_ns(ns->time_ns_for_children); + put_cgroup_ns(ns->cgroup_ns); + put_net(ns->net_ns); + kmem_cache_free(nsproxy_cachep, ns); +} + +DEFINE_FREE(nsproxy_free, struct nsproxy *, if (_T) nsproxy_free(_T)) + +void free_nsproxy(struct nsproxy *ns) +{ + nsproxy_ns_active_put(ns); + nsproxy_free(ns); +} + /* * Create new nsproxy and all of its the associated namespaces. * Return the newly created nsproxy. Do not attach this to the task, @@ -69,76 +90,45 @@ static struct nsproxy *create_new_namespaces(u64 flags, struct task_struct *tsk, struct user_namespace *user_ns, struct fs_struct *new_fs) { - struct nsproxy *new_nsp; - int err; + struct nsproxy *new_nsp __free(nsproxy_free) =3D NULL; =20 new_nsp =3D create_nsproxy(); if (!new_nsp) return ERR_PTR(-ENOMEM); =20 new_nsp->mnt_ns =3D copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, user_ns, new= _fs); - if (IS_ERR(new_nsp->mnt_ns)) { - err =3D PTR_ERR(new_nsp->mnt_ns); - goto out_ns; - } + if (IS_ERR(new_nsp->mnt_ns)) + return ERR_CAST(new_nsp->mnt_ns); =20 new_nsp->uts_ns =3D copy_utsname(flags, user_ns, tsk->nsproxy->uts_ns); - if (IS_ERR(new_nsp->uts_ns)) { - err =3D PTR_ERR(new_nsp->uts_ns); - goto out_uts; - } + if (IS_ERR(new_nsp->uts_ns)) + return ERR_CAST(new_nsp->uts_ns); =20 new_nsp->ipc_ns =3D copy_ipcs(flags, user_ns, tsk->nsproxy->ipc_ns); - if (IS_ERR(new_nsp->ipc_ns)) { - err =3D PTR_ERR(new_nsp->ipc_ns); - goto out_ipc; - } + if (IS_ERR(new_nsp->ipc_ns)) + return ERR_CAST(new_nsp->ipc_ns); =20 - new_nsp->pid_ns_for_children =3D - copy_pid_ns(flags, user_ns, tsk->nsproxy->pid_ns_for_children); - if (IS_ERR(new_nsp->pid_ns_for_children)) { - err =3D PTR_ERR(new_nsp->pid_ns_for_children); - goto out_pid; - } + new_nsp->pid_ns_for_children =3D copy_pid_ns(flags, user_ns, + tsk->nsproxy->pid_ns_for_children); + if (IS_ERR(new_nsp->pid_ns_for_children)) + return ERR_CAST(new_nsp->pid_ns_for_children); =20 new_nsp->cgroup_ns =3D copy_cgroup_ns(flags, user_ns, tsk->nsproxy->cgroup_ns); - if (IS_ERR(new_nsp->cgroup_ns)) { - err =3D PTR_ERR(new_nsp->cgroup_ns); - goto out_cgroup; - } + if (IS_ERR(new_nsp->cgroup_ns)) + return ERR_CAST(new_nsp->cgroup_ns); =20 new_nsp->net_ns =3D copy_net_ns(flags, user_ns, tsk->nsproxy->net_ns); - if (IS_ERR(new_nsp->net_ns)) { - err =3D PTR_ERR(new_nsp->net_ns); - goto out_net; - } + if (IS_ERR(new_nsp->net_ns)) + return ERR_CAST(new_nsp->net_ns); =20 new_nsp->time_ns_for_children =3D copy_time_ns(flags, user_ns, - tsk->nsproxy->time_ns_for_children); - if (IS_ERR(new_nsp->time_ns_for_children)) { - err =3D PTR_ERR(new_nsp->time_ns_for_children); - goto out_time; - } + tsk->nsproxy->time_ns_for_children); + if (IS_ERR(new_nsp->time_ns_for_children)) + return ERR_CAST(new_nsp->time_ns_for_children); new_nsp->time_ns =3D get_time_ns(tsk->nsproxy->time_ns); =20 - return new_nsp; - -out_time: - put_net(new_nsp->net_ns); -out_net: - put_cgroup_ns(new_nsp->cgroup_ns); -out_cgroup: - put_pid_ns(new_nsp->pid_ns_for_children); -out_pid: - put_ipc_ns(new_nsp->ipc_ns); -out_ipc: - put_uts_ns(new_nsp->uts_ns); -out_uts: - put_mnt_ns(new_nsp->mnt_ns); -out_ns: - kmem_cache_free(nsproxy_cachep, new_nsp); - return ERR_PTR(err); + return no_free_ptr(new_nsp); } =20 /* @@ -185,21 +175,6 @@ int copy_namespaces(u64 flags, struct task_struct *tsk) return 0; } =20 -void free_nsproxy(struct nsproxy *ns) -{ - nsproxy_ns_active_put(ns); - - put_mnt_ns(ns->mnt_ns); - put_uts_ns(ns->uts_ns); - put_ipc_ns(ns->ipc_ns); - put_pid_ns(ns->pid_ns_for_children); - put_time_ns(ns->time_ns); - put_time_ns(ns->time_ns_for_children); - put_cgroup_ns(ns->cgroup_ns); - put_net(ns->net_ns); - kmem_cache_free(nsproxy_cachep, ns); -} - /* * Called from unshare. Unshare all the namespaces part of nsproxy. * On success, returns the new nsproxy. @@ -338,7 +313,7 @@ static void put_nsset(struct nsset *nsset) if (nsset->fs && (flags & CLONE_NEWNS) && (flags & ~CLONE_NEWNS)) free_fs_struct(nsset->fs); if (nsset->nsproxy) - free_nsproxy(nsset->nsproxy); + nsproxy_free(nsset->nsproxy); } =20 static int prepare_nsset(unsigned flags, struct nsset *nsset) --=20 2.47.3