Commit 8f9f665a authored Jun 06, 2014 by Lai Jiangshan Committed by Linus Torvalds Jun 06, 2014

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>

parent 3afb69cb

lib/idr.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -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;