Commit 9e81eccf authored Jul 19, 2009 by Christian Lamparter Committed by John W. Linville Jul 21, 2009

cfg80211: double free in __cfg80211_scan_done



This patch fixes a double free corruption in __cfg80211_scan_done:

 ================================================
 BUG kmalloc-512: Object already free
 ------------------------------------------------

 INFO: Allocated in load_elf_binary+0x18b/0x19af age=6
 INFO: Freed in load_elf_binary+0x104e/0x19af age=5
 INFO: Slab 0xffffea0001bae4c0 objects=14 used=7
 INFO: Object 0xffff88007e8a9918 @offset=6424 fp=0xffff88007e8a9488

 Bytes b4 0xffff88007e8a9908:  00 00 00 00 00 00 00 00 5a 5a
 [...]
 Pid: 28705, comm: rmmod Tainted: P         C 2.6.31-rc2-wl #1
 Call Trace:
  [<ffffffff810da9f4>] print_trailer+0x14e/0x16e
  [<ffffffff810daa56>] object_err+0x42/0x61
  [<ffffffff810dbcd9>] __slab_free+0x2af/0x396
  [<ffffffffa0ec9694>] ? wiphy_unregister+0x92/0x142 [cfg80211]
  [<ffffffff810dd5e3>] kfree+0x13c/0x17a
  [<ffffffffa0ec9694>] ? wiphy_unregister+0x92/0x142 [cfg80211]
  [<ffffffffa0ec9694>] wiphy_unregister+0x92/0x142 [cfg80211]
  [<ffffffffa0eed163>] ieee80211_unregister_hw+0xc8/0xff [mac80211]
  [<ffffffffa0f3fbc8>] p54_unregister_common+0x31/0x66 [p54common]
  [...]
 FIX kmalloc-512: Object at 0xffff88007e8a9918 not freed

The code path which leads to the *funny* double free:

       request = rdev->scan_req;
       dev = dev_get_by_index(&init_net, request->ifidx);
	/*
	 * the driver was unloaded recently and
	 * therefore dev_get_by_index will return NULL!
	 */
        if (!dev)
                goto out;
	[...]
	rdev->scan_req = NULL; /* not executed... */
	[...]
 out:
        kfree(request);

Signed-off-by: Christian Lamparter <chunkeey@web.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

parent e56f0975

net/wireless/scan.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -35,8 +35,6 @@ void cfg80211_scan_done(struct cfg80211_scan_request *request, bool aborted)
		else
		nl80211_send_scan_done(wiphy_to_dev(request->wiphy), dev);

		wiphy_to_dev(request->wiphy)->scan_req = NULL;

		#ifdef CONFIG_WIRELESS_EXT
		if (!aborted) {
		memset(&wrqu, 0, sizeof(wrqu));
		@@ -48,6 +46,7 @@ void cfg80211_scan_done(struct cfg80211_scan_request *request, bool aborted)
		dev_put(dev);

		out:
		wiphy_to_dev(request->wiphy)->scan_req = NULL;
		kfree(request);
		}
		EXPORT_SYMBOL(cfg80211_scan_done);

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