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[2003:d9:93c9:8700:cb5f:a379:8c18:9fe1]) by smtp.googlemail.com with ESMTPSA id h5-v6sm13557841wrr.19.2018.07.12.11.53.13 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 12 Jul 2018 11:53:14 -0700 (PDT) From: Manfred Spraul To: Andrew Morton , Davidlohr Bueso , Dmitry Vyukov Cc: LKML , 1vier1@web.de, Kees Cook , Davidlohr Bueso , Manfred Spraul Subject: [PATCH 09/12] ipc: get rid of ids->tables_initialized hack Date: Thu, 12 Jul 2018 20:52:38 +0200 Message-Id: <20180712185241.4017-10-manfred@colorfullife.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180712185241.4017-1-manfred@colorfullife.com> References: <20180712185241.4017-1-manfred@colorfullife.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Davidlohr Bueso In sysvipc we have an ids->tables_initialized regarding the rhashtable, introduced in: commit 0cfb6aee70bd ("ipc: optimize semget/shmget/msgget for lots of keys") It's there, specifically, to prevent nil pointer dereferences, from using an uninitialized api. Considering how rhashtable_init() can fail (probably due to ENOMEM, if anything), this made the overall ipc initialization capable of failure as well. That alone is ugly, but fine, however I've spotted a few issues regarding the semantics of tables_initialized (however unlikely they may be): - There is inconsistency in what we return to userspace: ipc_addid() returns ENOSPC which is certainly _wrong_, while ipc_obtain_object_idr() returns EINVAL. - After we started using rhashtables, ipc_findkey() can return nil upon !tables_initialized, but the caller expects nil for when the ipc structure isn't found, and can therefore call into ipcget() callbacks. Now that rhashtable initialization cannot fail, we can properly get rid of the hack altogether. Signed-off-by: Davidlohr Bueso (commit id extended to 12 digits) Signed-off-by: Manfred Spraul --- include/linux/ipc_namespace.h | 1 - ipc/util.c | 23 ++++++++--------------- 2 files changed, 8 insertions(+), 16 deletions(-) diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h index b5630c8eb2f3..37f3a4b7c637 100644 --- a/include/linux/ipc_namespace.h +++ b/include/linux/ipc_namespace.h @@ -16,7 +16,6 @@ struct user_namespace; struct ipc_ids { int in_use; unsigned short seq; - bool tables_initialized; struct rw_semaphore rwsem; struct idr ipcs_idr; int max_id; diff --git a/ipc/util.c b/ipc/util.c index 234f6d781df3..f620778b11d2 100644 --- a/ipc/util.c +++ b/ipc/util.c @@ -125,7 +125,6 @@ int ipc_init_ids(struct ipc_ids *ids) if (err) return err; idr_init(&ids->ipcs_idr); - ids->tables_initialized = true; ids->max_id = -1; #ifdef CONFIG_CHECKPOINT_RESTORE ids->next_id = -1; @@ -178,19 +177,16 @@ void __init ipc_init_proc_interface(const char *path, const char *header, */ static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key) { - struct kern_ipc_perm *ipcp = NULL; + struct kern_ipc_perm *ipcp; - if (likely(ids->tables_initialized)) - ipcp = rhashtable_lookup_fast(&ids->key_ht, &key, + ipcp = rhashtable_lookup_fast(&ids->key_ht, &key, ipc_kht_params); + if (!ipcp) + return NULL; - if (ipcp) { - rcu_read_lock(); - ipc_lock_object(ipcp); - return ipcp; - } - - return NULL; + rcu_read_lock(); + ipc_lock_object(ipcp); + return ipcp; } /* @@ -268,7 +264,7 @@ int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int limit) if (limit > IPCMNI) limit = IPCMNI; - if (!ids->tables_initialized || ids->in_use >= limit) + if (ids->in_use >= limit) return -ENOSPC; idr_preload(GFP_KERNEL); @@ -577,9 +573,6 @@ struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id) struct kern_ipc_perm *out; int lid = ipcid_to_idx(id); - if (unlikely(!ids->tables_initialized)) - return ERR_PTR(-EINVAL); - out = idr_find(&ids->ipcs_idr, lid); if (!out) return ERR_PTR(-EINVAL); -- 2.17.1