From: Lai Jiangshan <laijs@cn.fujitsu.com>
Date: Fri, 6 Jun 2014 21:37:11 +0000 (-0700)
Subject: idr: fix unexpected ID-removal when idr_remove(unallocated_id)
X-Git-Tag: omap-for-v3.16/fixes-against-rc1~91^2~4^2~84
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8f9f665a707721146f24a892b1a0da1ab4da1d58;p=pandora-kernel.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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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