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: Kees Cook <keescook@chromium.org> Signed-off-by: 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>zero-colors
parent
5ccc8fb54f
commit
101ede01df
25
ipc/sem.c
25
ipc/sem.c
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@ -451,6 +451,25 @@ static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s)
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ipc_rmid(&sem_ids(ns), &s->sem_perm);
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ipc_rmid(&sem_ids(ns), &s->sem_perm);
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}
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}
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static struct sem_array *sem_alloc(size_t nsems)
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{
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struct sem_array *sma;
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size_t size;
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if (nsems > (INT_MAX - sizeof(*sma)) / sizeof(sma->sems[0]))
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return NULL;
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size = sizeof(*sma) + nsems * sizeof(sma->sems[0]);
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sma = kvmalloc(size, GFP_KERNEL);
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if (unlikely(!sma))
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return NULL;
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memset(sma, 0, size);
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atomic_set(&sma->sem_perm.refcount, 1);
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return sma;
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}
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/**
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/**
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* newary - Create a new semaphore set
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* newary - Create a new semaphore set
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* @ns: namespace
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* @ns: namespace
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@ -463,7 +482,6 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params)
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int id;
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int id;
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int retval;
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int retval;
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struct sem_array *sma;
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struct sem_array *sma;
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int size;
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key_t key = params->key;
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key_t key = params->key;
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int nsems = params->u.nsems;
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int nsems = params->u.nsems;
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int semflg = params->flg;
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int semflg = params->flg;
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@ -474,10 +492,7 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params)
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if (ns->used_sems + nsems > ns->sc_semmns)
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if (ns->used_sems + nsems > ns->sc_semmns)
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return -ENOSPC;
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return -ENOSPC;
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BUILD_BUG_ON(offsetof(struct sem_array, sem_perm) != 0);
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sma = sem_alloc(nsems);
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size = sizeof(*sma) + nsems * sizeof(sma->sems[0]);
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sma = container_of(ipc_rcu_alloc(size), struct sem_array, sem_perm);
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if (!sma)
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if (!sma)
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return -ENOMEM;
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return -ENOMEM;
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