[PATCH 3.16 182/202] netlabel: fix out-of-bounds memory accesses

[Ben Hutchings]

3.16.66-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Paul Moore <paul@xxxxxxxxxxxxxx>

commit 5578de4834fe0f2a34fedc7374be691443396d1f upstream.

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@xxxxxxxxxx>
Fixes: 446fda4f2682 ("[NetLabel]: CIPSOv4 engine")
Fixes: 3faa8f982f95 ("netlabel: Move bitmap manipulation functions to the NetLabel core.")
Signed-off-by: Paul Moore <paul@xxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[bwh: Backported to 3.16 following Paul's hint]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -165,7 +165,8 @@ static int cipso_v4_bitmap_walk(const un
 		    (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];
@@ -735,7 +736,8 @@ static int cipso_v4_map_lvl_valid(const
 	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;
 	}