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| author | Kees Cook <keescook@chromium.org> | 2017-07-12 14:35:05 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-07-12 16:26:01 -0700 |
| commit | 3e0c24042e5aa55eee817caeca67246df69931e1 (patch) | |
| tree | cbc852c2acea7b8f0dfd9e3f31dc4f6291a6e128 | |
| parent | 101ede01dfd5072651965e974bc6e30c8d0748e2 (diff) | |
| download | linux-3e0c24042e5aa55eee817caeca67246df69931e1.tar.gz linux-3e0c24042e5aa55eee817caeca67246df69931e1.tar.bz2 linux-3e0c24042e5aa55eee817caeca67246df69931e1.zip | |
ipc/shm: avoid ipc_rcu_alloc()
Instead of using ipc_rcu_alloc() which only performs the refcount bump,
open code it. This also allows for shmid_kernel structure layout to be
randomized in the future.
Link: http://lkml.kernel.org/r/20170525185107.12869-11-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/shm.c | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/ipc/shm.c b/ipc/shm.c index 566c1e193ee1..2ac489ef56e4 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -518,6 +518,19 @@ static const struct vm_operations_struct shm_vm_ops = { #endif }; +static struct shmid_kernel *shm_alloc(void) +{ + struct shmid_kernel *shp; + + shp = kvmalloc(sizeof(*shp), GFP_KERNEL); + if (unlikely(!shp)) + return NULL; + + atomic_set(&shp->shm_perm.refcount, 1); + + return shp; +} + /** * newseg - Create a new shared memory segment * @ns: namespace @@ -548,10 +561,7 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params) ns->shm_tot + numpages > ns->shm_ctlall) return -ENOSPC; - BUILD_BUG_ON(offsetof(struct shmid_kernel, shm_perm) != 0); - - shp = container_of(ipc_rcu_alloc(sizeof(*shp)), struct shmid_kernel, - shm_perm); + shp = shm_alloc(); if (!shp) return -ENOMEM; |