EDAC: Fix kernel panic on module unloading

This patch fixes use-after-free and double-free bugs in
edac_mc_sysfs_exit(). mci_pdev has single reference and put_device()
calls mc_attr_release() which calls kfree(). The following
device_del() works with already released memory. An another kfree() in
edac_mc_sysfs_exit() releses the same memory again. Great.

Signed-off-by: Konstantin Khlebnikov <[email protected]>
Cc: [email protected] # 3.[67]
Cc: Denis Kirjanov <[email protected]>
Cc: Mauro Carvalho Chehab <[email protected]>
Link: http://lkml.kernel.org/r/20121214110310.11019.21098.stgit@zurg
Signed-off-by: Borislav Petkov <[email protected]>

drivers/edac/edac_mc_sysfs.c

@@ -1159,8 +1159,7 @@ int __init edac_mc_sysfs_init(void)
 
 void __exit edac_mc_sysfs_exit(void)
 {
-	put_device(mci_pdev);
 	device_del(mci_pdev);
+	put_device(mci_pdev);
 	edac_put_sysfs_subsys();
-	kfree(mci_pdev);
 }