From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Davidlohr Bueso" , "Manfred Spraul" , "Linus Torvalds" , "Davidlohr Bueso" Date: Sun, 14 Oct 2018 16:25:41 +0100 Message-ID: Subject: [PATCH 3.16 063/366] ipc,shm: move BUG_ON check into shm_lock In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.16.60-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Davidlohr Bueso commit c5c8975b2eb4eb7604e8ce4f762987f56d2a96a2 upstream. Upon every shm_lock call, we BUG_ON if an error was returned, indicating racing either in idr or in shm_destroy. Move this logic into the locking. [akpm@linux-foundation.org: simplify code] Signed-off-by: Davidlohr Bueso Cc: Manfred Spraul Cc: Davidlohr Bueso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- ipc/shm.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) --- a/ipc/shm.c +++ b/ipc/shm.c @@ -155,8 +155,11 @@ static inline struct shmid_kernel *shm_l { struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id); - if (IS_ERR(ipcp)) - return (struct shmid_kernel *)ipcp; + /* + * We raced in the idr lookup or with shm_destroy(). Either way, the + * ID is busted. + */ + BUG_ON(IS_ERR(ipcp)); return container_of(ipcp, struct shmid_kernel, shm_perm); } @@ -190,7 +193,6 @@ static void shm_open(struct vm_area_stru struct shmid_kernel *shp; shp = shm_lock(sfd->ns, sfd->id); - BUG_ON(IS_ERR(shp)); shp->shm_atim = get_seconds(); shp->shm_lprid = task_tgid_vnr(current); shp->shm_nattch++; @@ -256,7 +258,6 @@ static void shm_close(struct vm_area_str down_write(&shm_ids(ns).rwsem); /* remove from the list of attaches of the shm segment */ shp = shm_lock(ns, sfd->id); - BUG_ON(IS_ERR(shp)); shp->shm_lprid = task_tgid_vnr(current); shp->shm_dtim = get_seconds(); shp->shm_nattch--; @@ -1199,7 +1200,6 @@ out_fput: out_nattch: down_write(&shm_ids(ns).rwsem); shp = shm_lock(ns, shmid); - BUG_ON(IS_ERR(shp)); shp->shm_nattch--; if (shm_may_destroy(ns, shp)) shm_destroy(ns, shp);