PM / hibernate: Avoid overflow in hibernate_preallocate_memory()
authorAaron Lu <aaron.lu@intel.com>
Wed, 6 Nov 2013 00:41:31 +0000 (08:41 +0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 4 Dec 2013 18:56:58 +0000 (10:56 -0800)
commit67b51f87ef941607e1e891bf477bd18df53ce6f1
treeb4fca418f3ef838d5d09c053c72b7856b2c78213
parentd8db1a5f3133ec936bcbaced67890f229551d24f
PM / hibernate: Avoid overflow in hibernate_preallocate_memory()

commit fd432b9f8c7c88428a4635b9f5a9c6e174df6e36 upstream.

When system has a lot of highmem (e.g. 16GiB using a 32 bits kernel),
the code to calculate how much memory we need to preallocate in
normal zone may cause overflow. As Leon has analysed:

 It looks that during computing 'alloc' variable there is overflow:
 alloc = (3943404 - 1970542) - 1978280 = -5418 (signed)
 And this function goes to err_out.

Fix this by avoiding that overflow.

References: https://bugzilla.kernel.org/show_bug.cgi?id=60817
Reported-and-tested-by: Leon Drugi <eyak@wp.pl>
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kernel/power/snapshot.c