[PATCH] ipc/shm: Use ERR_CAST() for shm_lock() error return

[Kees Cook]

This uses ERR_CAST() instead of an open-coded cast, as it is casting
across structure pointers, which upsets __randomize_layout:

ipc/shm.c: In function ‘shm_lock’:
ipc/shm.c:209:9: note: randstruct: casting between randomized structure pointer 
types (ssa): ‘struct shmid_kernel’ and ‘struct kern_ipc_perm’

  return (void *)ipcp;
         ^~~~~~~~~~~~

Fixes: 82061c57ce93 ("ipc: drop ipc_lock()")
Signed-off-by: Kees Cook <keesc...@chromium.org>
---
 ipc/shm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ipc/shm.c b/ipc/shm.c
index 4cd402e4cfeb..1c65fb357395 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -206,7 +206,7 @@ static inline struct shmid_kernel *shm_lock(struct 
ipc_namespace *ns, int id)
         * Callers of shm_lock() must validate the status of the returned ipc
         * object pointer and error out as appropriate.
         */
-       return (void *)ipcp;
+       return ERR_CAST(ipcp);
 }
 
 static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
-- 
2.17.1


-- 
Kees Cook
Pixel Security