openwrt/target/linux/brcm2708/patches-4.1/0173-vcsm-increment-res_stats-MAP_FAIL-stats-before-we-po.patch

From d3735e837e3102dfee2d2429c8043c9f4c673383 Mon Sep 17 00:00:00 2001
From: Colin Ian King <colin.king@canonical.com>
Date: Wed, 2 Sep 2015 07:27:36 -0400
Subject: [PATCH 173/203] vcsm: increment res_stats MAP_FAIL stats before we
 potentially release the resource

resource can be kfree'd when the reference count is zero, so we should
not bump the res_stats of the resource after the vmcs_sm_release_resource
call since the resource may have been kfree'd by this call. Instead, bump
the stats before we call vmcs_sm_release_resource to avoid a potential
NULL pointer derefernce.

Bug found using cppcheck static analysis:

[drivers/char/broadcom/vc_sm/vmcs_sm.c:1373]: (error) Dereferencing
  'resource' after it is deallocated / released

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/char/broadcom/vc_sm/vmcs_sm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/char/broadcom/vc_sm/vmcs_sm.c
+++ b/drivers/char/broadcom/vc_sm/vmcs_sm.c
@@ -1368,8 +1368,8 @@ static int vc_sm_mmap(struct file *file,
 	return 0;
 
 error:
-	vmcs_sm_release_resource(resource, 0);
 	resource->res_stats[MAP_FAIL]++;
+	vmcs_sm_release_resource(resource, 0);
 	return ret;
 }