netlabel: fix out-of-bounds memory accesses

There are two array out-of-bounds memory accesses, one in
cipso_v4_map_lvl_valid(), the other in netlbl_bitmap_walk().  Both
errors are embarassingly simple, and the fixes are straightforward.

As a FYI for anyone backporting this patch to kernels prior to v4.8,
you'll want to apply the netlbl_bitmap_walk() patch to
cipso_v4_bitmap_walk() as netlbl_bitmap_walk() doesn't exist before
Linux v4.8.

Reported-by: Jann Horn <jannh@google.com>
Fixes: 446fda4f2682 ("[NetLabel]: CIPSOv4 engine")
Fixes: 3faa8f982f95 ("netlabel: Move bitmap manipulation functions to the NetLabel core.")
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 4 insertions, 2 deletions

diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index eff86a71c1b0..f0165c5f376b 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -667,7 +667,8 @@ static int cipso_v4_map_lvl_valid(const struct cipso_v4_doi *doi_def, u8 level)
         case CIPSO_V4_MAP_PASS:
                 return 0;
         case CIPSO_V4_MAP_TRANS:
-                if (doi_def->map.std->lvl.cipso[level] < CIPSO_V4_INV_LVL)
+                if ((level < doi_def->map.std->lvl.cipso_size) &&
+                    (doi_def->map.std->lvl.cipso[level] < CIPSO_V4_INV_LVL))
                         return 0;
                 break;
         }
diff --git a/net/netlabel/netlabel_kapi.c b/net/netlabel/netlabel_kapi.c
index ea7c67050792..ee3e5b6471a6 100644
--- a/net/netlabel/netlabel_kapi.c
+++ b/net/netlabel/netlabel_kapi.c
@@ -903,7 +903,8 @@ int netlbl_bitmap_walk(const unsigned char *bitmap, u32 bitmap_len,
                     (state == 0 && (byte & bitmask) == 0))
                         return bit_spot;
 
-                bit_spot++;
+                if (++bit_spot >= bitmap_len)
+                        return -1;
                 bitmask >>= 1;
                 if (bitmask == 0) {
                         byte = bitmap[++byte_offset];