| From: Davidlohr Bueso <dave@stgolabs.net> |
| Date: Tue, 30 Jun 2015 14:58:36 -0700 |
| Subject: ipc,shm: move BUG_ON check into shm_lock |
| |
| 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 <dbueso@suse.de> |
| Cc: Manfred Spraul <manfred@colorfullife.com> |
| Cc: Davidlohr Bueso <dave@stgolabs.net> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| 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); |