From 9405c03ee778cd3e353e55fff6e16dfdd9609c02 Mon Sep 17 00:00:00 2001
From: Elena Reshetova <elena.reshetova@intel.com>
Date: Fri, 8 Sep 2017 16:17:45 -0700
Subject: [PATCH] ipc: convert kern_ipc_perm.refcount from atomic_t to
refcount_t
refcount_t type and corresponding API should be used instead of atomic_t
when the variable is used as a reference counter. This allows to avoid
accidental refcounter overflows that might lead to use-after-free
situations.
Link: http://lkml.kernel.org/r/1499417992-3238-4-git-send-email-elena.reshetova@intel.com
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: <arozansk@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
include/linux/ipc.h | 3 ++-
ipc/util.c | 6 +++---
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/include/linux/ipc.h b/include/linux/ipc.h
index fadd579d577dc..ae68980e9d481 100644
--- a/include/linux/ipc.h
+++ b/include/linux/ipc.h
@@ -4,6 +4,7 @@
#include <linux/spinlock.h>
#include <linux/uidgid.h>
#include <uapi/linux/ipc.h>
+#include <linux/refcount.h>
#define IPCMNI 32768 /* <= MAX_INT limit for ipc arrays (including sysctl changes) */
@@ -22,7 +23,7 @@ struct kern_ipc_perm {
void *security;
struct rcu_head rcu;
- atomic_t refcount;
+ refcount_t refcount;
} ____cacheline_aligned_in_smp __randomize_layout;
#endif /* _LINUX_IPC_H */
diff --git a/ipc/util.c b/ipc/util.c
index 1a2cb02467ab5..069bb22c9f642 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -232,7 +232,7 @@ int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int size)
idr_preload(GFP_KERNEL);
- atomic_set(&new->refcount, 1);
+ refcount_set(&new->refcount, 1);
spin_lock_init(&new->lock);
new->deleted = false;
rcu_read_lock();
@@ -397,13 +397,13 @@ void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
int ipc_rcu_getref(struct kern_ipc_perm *ptr)
{
- return atomic_inc_not_zero(&ptr->refcount);
+ return refcount_inc_not_zero(&ptr->refcount);
}
void ipc_rcu_putref(struct kern_ipc_perm *ptr,
void (*func)(struct rcu_head *head))
{
- if (!atomic_dec_and_test(&ptr->refcount))
+ if (!refcount_dec_and_test(&ptr->refcount))
return;
call_rcu(&ptr->rcu, func);
--
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