EDAC: Fix kernel panic on module unloading

commit 311bd84247ee0bedae6cdfbfc5e2c3450f9decd1 upstream.

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 <khlebnikov@openvz.org>
Cc: Denis Kirjanov <kirjanov@gmail.com>
Cc: Mauro Carvalho Chehab <mchehab@redhat.com>
Link: http://lkml.kernel.org/r/20121214110310.11019.21098.stgit@zurg
Signed-off-by: Borislav Petkov <bp@alien8.de>
[ a partial 3.7.y backport ]
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/edac/edac_mc_sysfs.c b/drivers/edac/edac_mc_sysfs.c
index ed0bc07b85039deb78c09812e461e0c41e3b3670..fe4fa1cde67e6c8348bcd8a1a98cd2e91530a3f6 100644 (file)
--- a/drivers/edac/edac_mc_sysfs.c
+++ b/drivers/edac/edac_mc_sysfs.c
@@ -1145,7 +1145,7 @@ 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();
 }