Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 101ede01 authored by Kees Cook's avatar Kees Cook Committed by Linus Torvalds
Browse files

ipc/sem: avoid ipc_rcu_alloc() 

Instead of using ipc_rcu_alloc() which only performs the refcount bump,
open code it to perform better sem-specific checks.  This also allows
for sem_array structure layout to be randomized in the future.

[manfred@colorfullife.com: Rediff, because the memset was temporarily inside ipc_rcu_alloc()]
Link: http://lkml.kernel.org/r/20170525185107.12869-10-manfred@colorfullife.com


Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarManfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5ccc8fb5

ipc/sem.c

+20 −5
Original line number Diff line number Diff line
@@ -451,6 +451,25 @@ static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s) 
	ipc_rmid(&sem_ids(ns), &s->sem_perm);

}



static struct sem_array *sem_alloc(size_t nsems)

{

	struct sem_array *sma;

	size_t size;



	if (nsems > (INT_MAX - sizeof(*sma)) / sizeof(sma->sems[0]))

		return NULL;



	size = sizeof(*sma) + nsems * sizeof(sma->sems[0]);

	sma = kvmalloc(size, GFP_KERNEL);

	if (unlikely(!sma))

		return NULL;



	memset(sma, 0, size);

	atomic_set(&sma->sem_perm.refcount, 1);



	return sma;

}



/**

 * newary - Create a new semaphore set

 * @ns: namespace
@@ -463,7 +482,6 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params) 
	int id;

	int retval;

	struct sem_array *sma;

	int size;

	key_t key = params->key;

	int nsems = params->u.nsems;

	int semflg = params->flg;
@@ -474,10 +492,7 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params) 
	if (ns->used_sems + nsems > ns->sc_semmns)

		return -ENOSPC;



	BUILD_BUG_ON(offsetof(struct sem_array, sem_perm) != 0);



	size = sizeof(*sma) + nsems * sizeof(sma->sems[0]);

	sma = container_of(ipc_rcu_alloc(size), struct sem_array, sem_perm);

	sma = sem_alloc(nsems);

	if (!sma)

		return -ENOMEM;