Since idtree assigns sequentially, it rarely reaches high numbers.

But such numbers can be forced with idr_get_new_above(), and that
reveals two bugs:

1) Crash in sub_remove() caused by pa array being too short.
2) Shift by more than 32 in _idr_find(), which is undefined, causing
   the "outside the current tree" optimization to misfire and return NULL.

1 files changed, 5 insertions, 3 deletions

diff --git a/lib/util/idtree.c b/lib/util/idtree.c
index 0af93a229d..c14796101a 100644
--- a/lib/util/idtree.c
+++ b/lib/util/idtree.c
@@ -240,7 +240,7 @@ build_up:
 static int sub_remove(struct idr_context *idp, int shift, int id)
 {
 	struct idr_layer *p = idp->top;
-	struct idr_layer **pa[MAX_LEVEL];
+	struct idr_layer **pa[1+MAX_LEVEL];
 	struct idr_layer ***paa = &pa[0];
 	int n;
 
@@ -280,8 +280,10 @@ static void *_idr_find(struct idr_context *idp, int id)
 	 * This tests to see if bits outside the current tree are
 	 * present.  If so, tain't one of ours!
 	 */
-	if ((id & ~(~0 << MAX_ID_SHIFT)) >> (n + IDR_BITS))
-	     return NULL;
+	if (n + IDR_BITS < 31 &&
+	    ((id & ~(~0 << MAX_ID_SHIFT)) >> (n + IDR_BITS))) {
+		return NULL;
+	}
 
 	/* Mask off upper bits we don't use for the search. */
 	id &= MAX_ID_MASK;