From: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx> Subject: ipc/sem.c: avoid ipc_rcu_putref for failed ipc_addid() Loosely based on a patch from Kees Cook <keescook@xxxxxxxxxxxx>: - id and retval can be merged - if ipc_addid() fails, then use call_rcu() directly. The difference is that call_rcu is used for failed ipc_addid() calls, to continue to guaranteed an rcu delay for security_sem_free(). Link: http://lkml.kernel.org/r/20170525185107.12869-14-manfred@xxxxxxxxxxxxxxxx Signed-off-by: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- ipc/sem.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff -puN ipc/sem.c~ipc-semc-avoid-ipc_rcu_putref-for-failed-ipc_addid ipc/sem.c --- a/ipc/sem.c~ipc-semc-avoid-ipc_rcu_putref-for-failed-ipc_addid +++ a/ipc/sem.c @@ -479,7 +479,6 @@ static struct sem_array *sem_alloc(size_ */ static int newary(struct ipc_namespace *ns, struct ipc_params *params) { - int id; int retval; struct sem_array *sma; key_t key = params->key; @@ -520,10 +519,10 @@ static int newary(struct ipc_namespace * sma->sem_nsems = nsems; sma->sem_ctime = get_seconds(); - id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni); - if (id < 0) { - ipc_rcu_putref(&sma->sem_perm, sem_rcu_free); - return id; + retval = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni); + if (retval < 0) { + call_rcu(&sma->sem_perm.rcu, sem_rcu_free); + return retval; } ns->used_sems += nsems; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
