From: Lai Jiangshan <laijs@cn.fujitsu.com>
Date: Thu, 22 May 2014 00:44:08 +0000 (+1000)
Subject: idr: fix unexpected ID-removal when idr_remove(unallocated_id)
X-Git-Tag: next-20140530~2^2~52
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=a0f9d0cee7e3ca3319f62b3a3cde88601199f3c4;p=karo-tx-linux.git

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>
---

diff --git a/lib/idr.c b/lib/idr.c
index 4df67928816e..c4afd94bdf69 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -562,6 +562,11 @@ void idr_remove(struct idr *idp, int id)
 	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 @@ void ida_remove(struct ida *ida, int id)
 	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;