From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Elena Reshetova To: gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, netdev@vger.kernel.org, linux1394-devel@lists.sourceforge.net, linux-bcache@vger.kernel.org, linux-raid@vger.kernel.org, linux-media@vger.kernel.org, devel@linuxdriverproject.org, linux-pci@vger.kernel.org, linux-s390@vger.kernel.org, fcoe-devel@open-fcoe.org, linux-scsi@vger.kernel.org, open-iscsi@googlegroups.com, devel@driverdev.osuosl.org, target-devel@vger.kernel.org, linux-serial@vger.kernel.org, linux-usb@vger.kernel.org, peterz@infradead.org, Elena Reshetova , Hans Liljestrand , Kees Cook , David Windsor Subject: [PATCH 29/29] drivers, xen: convert grant_map.users from atomic_t to refcount_t Date: Mon, 6 Mar 2017 16:21:16 +0200 Message-Id: <1488810076-3754-30-git-send-email-elena.reshetova@intel.com> In-Reply-To: <1488810076-3754-1-git-send-email-elena.reshetova@intel.com> References: <1488810076-3754-1-git-send-email-elena.reshetova@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: 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 Signed-off-by: Hans Liljestrand Signed-off-by: Kees Cook Signed-off-by: David Windsor --- drivers/xen/gntdev.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c index 2ef2b61..b183cb2 100644 --- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -35,6 +35,7 @@ #include #include #include +#include #include #include @@ -85,7 +86,7 @@ struct grant_map { int index; int count; int flags; - atomic_t users; + refcount_t users; struct unmap_notify notify; struct ioctl_gntdev_grant_ref *grants; struct gnttab_map_grant_ref *map_ops; @@ -165,7 +166,7 @@ static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count) add->index = 0; add->count = count; - atomic_set(&add->users, 1); + refcount_set(&add->users, 1); return add; @@ -211,7 +212,7 @@ static void gntdev_put_map(struct gntdev_priv *priv, struct grant_map *map) if (!map) return; - if (!atomic_dec_and_test(&map->users)) + if (!refcount_dec_and_test(&map->users)) return; atomic_sub(map->count, &pages_mapped); @@ -399,7 +400,7 @@ static void gntdev_vma_open(struct vm_area_struct *vma) struct grant_map *map = vma->vm_private_data; pr_debug("gntdev_vma_open %p\n", vma); - atomic_inc(&map->users); + refcount_inc(&map->users); } static void gntdev_vma_close(struct vm_area_struct *vma) @@ -1003,7 +1004,7 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma) goto unlock_out; } - atomic_inc(&map->users); + refcount_inc(&map->users); vma->vm_ops = &gntdev_vmops; -- 2.7.4