minios: correct char array allocation for xenbus paths

The char arrays used to hold xenbus paths have historically been
allocated by manually counting the length longest string constants
included in constructing the path. This has led to improperly sized
buffers, both too large (with little consequence) and too small (which
obviously causes problems). This patch corrects the instances where
the length was incorrectly calculated by using strlen() on the longest
string constant used in building a xenbus path.

A follow-on clean-up patch will change all instances to use strlen().

Signed-off-by: Ben Cressey <bcressey@amazon.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-By: Samuel Thibault <samuel.thibault@ens-lyon.org>
[msw: split this patch from a larger patch from Ben, reworked to use
 strlen()]
Signed-off-by: Matt Wilson <msw@amazon.com>

1 files changed, 5 insertions, 5 deletions

diff --git a/extras/mini-os/fbfront.c b/extras/mini-os/fbfront.c
index 54a5e67f6c..6eddb3cca3 100644
--- a/extras/mini-os/fbfront.c
+++ b/extras/mini-os/fbfront.c
@@ -158,8 +158,8 @@ done:
 
     {
         XenbusState state;
-        char path[strlen(dev->backend) + 1 + 6 + 1];
-        char frontpath[strlen(nodename) + 1 + 6 + 1];
+        char path[strlen(dev->backend) + strlen("/state") + 1];
+        char frontpath[strlen(nodename) + strlen("/state") + 1];
 
         snprintf(path, sizeof(path), "%s/state", dev->backend);
 
@@ -240,7 +240,7 @@ void shutdown_kbdfront(struct kbdfront_dev *dev)
     XenbusState state;
 
     char path[strlen(dev->backend) + 1 + 5 + 1];
-    char nodename[strlen(dev->nodename) + 1 + 5 + 1];
+    char nodename[strlen(dev->nodename) + strlen("/request-abs-pointer") + 1];
 
     printk("close kbd: backend at %s\n",dev->backend);
 
@@ -521,7 +521,7 @@ done:
     {
         XenbusState state;
         char path[strlen(dev->backend) + 1 + 14 + 1];
-        char frontpath[strlen(nodename) + 1 + 6 + 1];
+        char frontpath[strlen(nodename) + strlen("/state") + 1];
 
         snprintf(path, sizeof(path), "%s/state", dev->backend);
 
@@ -632,7 +632,7 @@ void shutdown_fbfront(struct fbfront_dev *dev)
     XenbusState state;
 
     char path[strlen(dev->backend) + 1 + 5 + 1];
-    char nodename[strlen(dev->nodename) + 1 + 5 + 1];
+    char nodename[strlen(dev->nodename) + strlen("/feature-update") + 1];
 
     printk("close fb: backend at %s\n",dev->backend);