From: Aaron Lu Date: Wed, 6 Nov 2013 00:41:31 +0000 (+0800) Subject: PM / hibernate: Avoid overflow in hibernate_preallocate_memory() X-Git-Tag: firefly_0821_release~176^2~4983^2~3^2 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=fd432b9f8c7c88428a4635b9f5a9c6e174df6e36;p=firefly-linux-kernel-4.4.55.git PM / hibernate: Avoid overflow in hibernate_preallocate_memory() 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 Cc: All applicable Signed-off-by: Aaron Lu Signed-off-by: Rafael J. Wysocki --- diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c index 98c3b34a4cff..10c22cae83a0 100644 --- a/kernel/power/snapshot.c +++ b/kernel/power/snapshot.c @@ -1402,7 +1402,11 @@ int hibernate_preallocate_memory(void) * highmem and non-highmem zones separately. */ pages_highmem = preallocate_image_highmem(highmem / 2); - alloc = (count - max_size) - pages_highmem; + alloc = count - max_size; + if (alloc > pages_highmem) + alloc -= pages_highmem; + else + alloc = 0; pages = preallocate_image_memory(alloc, avail_normal); if (pages < alloc) { /* We have exhausted non-highmem pages, try highmem. */