The patch titled
Subject: ipc/shm: avoid ipc_rcu_alloc()
has been added to the -mm tree. Its filename is
ipc-shm-avoid-ipc_rcu_alloc.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ipc-shm-avoid-ipc_rcu_alloc.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ipc-shm-avoid-ipc_rcu_alloc.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Kees Cook <keescook@xxxxxxxxxxxx>
Subject: 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@xxxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
ipc/shm.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
diff -puN ipc/shm.c~ipc-shm-avoid-ipc_rcu_alloc ipc/shm.c
--- a/ipc/shm.c~ipc-shm-avoid-ipc_rcu_alloc
+++ a/ipc/shm.c
@@ -518,6 +518,19 @@ static const struct vm_operations_struct
#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->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;
_
Patches currently in -mm which might be from keescook@xxxxxxxxxxxx are
ipc-drop-non-rcu-allocation.patch
ipc-sem-do-not-use-ipc_rcu_free.patch
ipc-shm-do-not-use-ipc_rcu_free.patch
ipc-msg-do-not-use-ipc_rcu_free.patch
ipc-util-drop-ipc_rcu_free.patch
ipc-sem-avoid-ipc_rcu_alloc.patch
ipc-shm-avoid-ipc_rcu_alloc.patch
ipc-msg-avoid-ipc_rcu_alloc.patch
ipc-util-drop-ipc_rcu_alloc.patch
ipc-move-atomic_set-to-where-it-is-needed.patch
ipc-shm-remove-special-shm_alloc-free.patch
ipc-msg-remove-special-msg_alloc-free.patch
ipc-sem-drop-__sem_free.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
