lkml.org 
[lkml]   [2017]   [Jul]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 3/3] ipc: convert kern_ipc_perm.refcount from atomic_t to refcount_t
Date
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.

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>
---
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 fadd579..ae68980 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 1a2cb02..069bb22 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);
--
2.7.4
\
 
 \ /
  Last update: 2017-07-07 11:01    [W:0.091 / U:10.256 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site