idr: fix unexpected ID-removal when idr_remove(unallocated_id)
If unallocated_id = (ANY * idr_max(idp->layers) + existing_id) is passed
to idr_remove(). The existing_id will be removed unexpectedly.
The following test shows this unexpected id-removal:
static void test4(void)
{
int id;
DEFINE_IDR(test_idr);
printk(KERN_INFO "Start test4\n");
id = idr_alloc(&test_idr, (void *)1, 42, 43, GFP_KERNEL);
BUG_ON(id != 42);
idr_remove(&test_idr, 42 + IDR_SIZE);
TEST_BUG_ON(idr_find(&test_idr, 42) != (void *)1);
idr_destroy(&test_idr);
printk(KERN_INFO "End of test4\n");
}
ida_remove() shares the similar problem.
It happens only when the caller tries to free an unallocated ID which is
the caller's fault. It is not a bug. But it is better to add the
proper check and complain rather than removing an existing_id silently.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/lib/idr.c b/lib/idr.c
index 4df6792..c4afd94 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -562,6 +562,11 @@
if (id < 0)
return;
+ if (id > idr_max(idp->layers)) {
+ idr_remove_warning(id);
+ return;
+ }
+
sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
if (idp->top && idp->top->count == 1 && (idp->layers > 1) &&
idp->top->ary[0]) {
@@ -1025,6 +1030,9 @@
int n;
struct ida_bitmap *bitmap;
+ if (idr_id > idr_max(ida->idr.layers))
+ goto err;
+
/* clear full bits while looking up the leaf idr_layer */
while ((shift > 0) && p) {
n = (idr_id >> shift) & IDR_MASK;