linux-kernel - [PATCH v2 1/7] drivers:hv: Lock access to hyperv

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1459381727-25039-2-git-send-email-jakeo@microsoft.com>
Date:	Wed, 30 Mar 2016 16:48:41 -0700
From:	Jake Oshins <jakeo@...rosoft.com>
To:	linux-pci@...r.kernel.org, gregkh@...uxfoundation.org,
	kys@...rosoft.com, linux-kernel@...r.kernel.org,
	devel@...uxdriverproject.org, olaf@...fle.de, apw@...onical.com,
	vkuznets@...hat.com, haiyangz@...rosoft.com, haddenh@...rosoft.com
Cc:	Jake Oshins <jakeo@...rosoft.com>
Subject: [PATCH v2 1/7] drivers:hv: Lock access to hyperv_mmio resource tree

In existing code, this tree of resources is created
in single-threaded code and never modified after it is
created, and thus needs no locking.  This patch introduces
a semaphore for tree access, as other patches in this
series introduce run-time modifications of this resource
tree which can happen on multiple threads.

Signed-off-by: Jake Oshins <jakeo@...rosoft.com>
---
 drivers/hv/vmbus_drv.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 64713ff..799518b 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -102,6 +102,7 @@ static struct notifier_block hyperv_panic_block = {
 };

 struct resource *hyperv_mmio;
+DEFINE_SEMAPHORE(hyperv_mmio_lock);

 static int vmbus_exists(void)
 {
@@ -1132,7 +1133,10 @@ int vmbus_allocate_mmio(struct resource **new, struct hv_device *device_obj,
 	resource_size_t range_min, range_max, start, local_min, local_max;
 	const char *dev_n = dev_name(&device_obj->device);
 	u32 fb_end = screen_info.lfb_base + (screen_info.lfb_size << 1);
-	int i;
+	int i, retval;
+
+	retval = -ENXIO;
+	down(&hyperv_mmio_lock);

 	for (iter = hyperv_mmio; iter; iter = iter->sibling) {
 		if ((iter->start >= max) || (iter->end <= min))
@@ -1169,13 +1173,17 @@ int vmbus_allocate_mmio(struct resource **new, struct hv_device *device_obj,
 			for (; start + size - 1 <= local_max; start += align) {
 				*new = request_mem_region_exclusive(start, size,
 								    dev_n);
-				if (*new)
-					return 0;
+				if (*new) {
+					retval = 0;
+					goto exit;
+				}
 			}
 		}
 	}

-	return -ENXIO;
+exit:
+	up(&hyperv_mmio_lock);
+	return retval;
 }
 EXPORT_SYMBOL_GPL(vmbus_allocate_mmio);

--
1.9.1