NetLabel: better error handling involving mls_export_cat()

Upon inspection it looked like the error handling for mls_export_cat() was
rather poor.  This patch addresses this by NULL'ing out kfree()'d pointers
before returning and checking the return value of the function everywhere
it is called.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/security/selinux/ss/ebitmap.c b/security/selinux/ss/ebitmap.c
index cfed1d30fa6a..d539346ab3a2 100644
--- a/security/selinux/ss/ebitmap.c
+++ b/security/selinux/ss/ebitmap.c
@@ -93,11 +93,15 @@ int ebitmap_export(const struct ebitmap *src,
         size_t bitmap_byte;
         unsigned char bitmask;
 
+        if (src->highbit == 0) {
+                *dst = NULL;
+                *dst_len = 0;
+                return 0;
+        }
+
         bitmap_len = src->highbit / 8;
         if (src->highbit % 7)
                 bitmap_len += 1;
-        if (bitmap_len == 0)
-                return -EINVAL;
 
         bitmap = kzalloc((bitmap_len & ~(sizeof(MAPTYPE) - 1)) +
                          sizeof(MAPTYPE),