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authorKees Cook <keescook@chromium.org>2017-07-12 14:35:05 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-07-12 16:26:01 -0700
commit3e0c24042e5aa55eee817caeca67246df69931e1 (patch)
treecbc852c2acea7b8f0dfd9e3f31dc4f6291a6e128 /ipc
parent101ede01dfd5072651965e974bc6e30c8d0748e2 (diff)
downloadlinux-sh-3e0c24042e5aa55eee817caeca67246df69931e1.tar.gz
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>
Diffstat (limited to 'ipc')
-rw-r--r--ipc/shm.c18
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;