Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1650755

[PATCH 10/20] ipc/shm: Avoid ipc_rcu_alloc()

Show all headers | View raw

From: Kees Cook <keescook@chromium.org>

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.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
---
 ipc/shm.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/ipc/shm.c b/ipc/shm.c
index 77e1bff..c9f1f30 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;
 
-- 
2.9.3

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 0/20 V3] Misc cleanups for ipc Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 05/20] ipc/sem: Do not use ipc_rcu_free() Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 08/20] ipc/util: Drop ipc_rcu_free() Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 15/20] ipc/msg.c: Avoid ipc_rcu_putref for failed ipc_addid() Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 19/20] ipc/sem: Drop __sem_free() Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 20/20] ipc/util.h: Update documentation for ipc_getref() and ipc_putref() Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 09/20] ipc/sem: Avoid ipc_rcu_alloc() Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 17/20] ipc/shm: Remove special shm_alloc/free Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 11/20] ipc/msg: Avoid ipc_rcu_alloc() Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 12/20] ipc/util: Drop ipc_rcu_alloc() Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 16/20] ipc: Move atomic_set() to where it is needed Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 04/20] ipc: Drop non-RCU allocation Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
    Re: [PATCH 04/20] ipc: Drop non-RCU allocation Kees Cook <keescook@chromium.org> - 2017-05-25 21:40 +0200
  [PATCH 03/20] include/linux/sem.h: Correctly document sem_ctime Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 07/20] ipc/msg: Do not use ipc_rcu_free() Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 10/20] ipc/shm: Avoid ipc_rcu_alloc() Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  Re: [PATCH 0/20 V3] Misc cleanups for ipc Kees Cook <keescook@chromium.org> - 2017-05-25 21:50 +0200
    Re: [PATCH 0/20 V3] Misc cleanups for ipc Manfred Spraul <manfred@colorfullife.com> - 2017-05-26 04:00 +0200

csiph-web