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| author | Kees Cook <keescook@chromium.org> | 2017-07-12 14:35:02 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-07-12 16:26:01 -0700 |
| commit | 101ede01dfd5072651965e974bc6e30c8d0748e2 (patch) | |
| tree | de85b9884a50812354b9f9ccdc3193a30239fa4d | |
| parent | 5ccc8fb54f1c083f1dc7e073150ec18d43457872 (diff) | |
| download | linux-101ede01dfd5072651965e974bc6e30c8d0748e2.tar.gz linux-101ede01dfd5072651965e974bc6e30c8d0748e2.tar.bz2 linux-101ede01dfd5072651965e974bc6e30c8d0748e2.zip | |
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>
| -rw-r--r-- | ipc/sem.c | 25 |
1 files changed, 20 insertions, 5 deletions
diff --git a/ipc/sem.c b/ipc/sem.c index a04c4d6d120c..445a5b5eb88f 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -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; |