ipc: make shm_get_stat() more robust

shm_get_stat() assumes idr_find(&shm_ids(ns).ipcs_idr) returns "struct shmid_kernel *"; all other callers assume that it returns "struct kern_ipc_perm *". This works because "struct kern_ipc_perm" is currently the first member of "struct shmid_kernel", but it would be better to use container_of() to prevent future breakage. Signed-off-by: Tony Battersby <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Jiri Kosina <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
kishon · Apr 3, 2009 · e562aeb · e562aeb
1 parent 40e8a10
commit e562aeb
Showing 1 changed file with 4 additions and 2 deletions.
diff --git a/ipc/shm.c b/ipc/shm.c
@@ -555,12 +555,14 @@ static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
 	in_use = shm_ids(ns).in_use;
 
 	for (total = 0, next_id = 0; total < in_use; next_id++) {
+		struct kern_ipc_perm *ipc;
 		struct shmid_kernel *shp;
 		struct inode *inode;
 
-		shp = idr_find(&shm_ids(ns).ipcs_idr, next_id);
-		if (shp == NULL)
+		ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
+		if (ipc == NULL)
 			continue;
+		shp = container_of(ipc, struct shmid_kernel, shm_perm);
 
 		inode = shp->shm_file->f_path.dentry->d_inode;