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 --- 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 } #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) #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; } +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) = NULL; new_nsp = create_nsproxy(); if (!new_nsp) return ERR_PTR(-ENOMEM); new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, user_ns, new_fs); - if (IS_ERR(new_nsp->mnt_ns)) { - err = PTR_ERR(new_nsp->mnt_ns); - goto out_ns; - } + if (IS_ERR(new_nsp->mnt_ns)) + return ERR_CAST(new_nsp->mnt_ns); new_nsp->uts_ns = copy_utsname(flags, user_ns, tsk->nsproxy->uts_ns); - if (IS_ERR(new_nsp->uts_ns)) { - err = PTR_ERR(new_nsp->uts_ns); - goto out_uts; - } + if (IS_ERR(new_nsp->uts_ns)) + return ERR_CAST(new_nsp->uts_ns); new_nsp->ipc_ns = copy_ipcs(flags, user_ns, tsk->nsproxy->ipc_ns); - if (IS_ERR(new_nsp->ipc_ns)) { - err = PTR_ERR(new_nsp->ipc_ns); - goto out_ipc; - } + if (IS_ERR(new_nsp->ipc_ns)) + return ERR_CAST(new_nsp->ipc_ns); - new_nsp->pid_ns_for_children = - copy_pid_ns(flags, user_ns, tsk->nsproxy->pid_ns_for_children); - if (IS_ERR(new_nsp->pid_ns_for_children)) { - err = PTR_ERR(new_nsp->pid_ns_for_children); - goto out_pid; - } + new_nsp->pid_ns_for_children = 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); new_nsp->cgroup_ns = copy_cgroup_ns(flags, user_ns, tsk->nsproxy->cgroup_ns); - if (IS_ERR(new_nsp->cgroup_ns)) { - err = PTR_ERR(new_nsp->cgroup_ns); - goto out_cgroup; - } + if (IS_ERR(new_nsp->cgroup_ns)) + return ERR_CAST(new_nsp->cgroup_ns); new_nsp->net_ns = copy_net_ns(flags, user_ns, tsk->nsproxy->net_ns); - if (IS_ERR(new_nsp->net_ns)) { - err = PTR_ERR(new_nsp->net_ns); - goto out_net; - } + if (IS_ERR(new_nsp->net_ns)) + return ERR_CAST(new_nsp->net_ns); new_nsp->time_ns_for_children = copy_time_ns(flags, user_ns, - tsk->nsproxy->time_ns_for_children); - if (IS_ERR(new_nsp->time_ns_for_children)) { - err = 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 = get_time_ns(tsk->nsproxy->time_ns); - 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); } /* @@ -185,21 +175,6 @@ int copy_namespaces(u64 flags, struct task_struct *tsk) return 0; } -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); } static int prepare_nsset(unsigned flags, struct nsset *nsset) -- 2.47.3