x86: add boundary check for 32bit res before expand e820 resource to alignment

fix hang with HIGHMEM_64G and 32bit resource.  According to hpa and
Linus, use (resource_size_t)-1 to fend off big ranges.

Analyzed by hpa

Reported-and-tested-by: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 6 deletions

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 7271fa33d791..c4ca89d9aaf4 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -1383,6 +1383,8 @@ static unsigned long ram_alignment(resource_size_t pos)
         return 32*1024*1024;
 }
 
+#define MAX_RESOURCE_SIZE ((resource_size_t)-1)
+
 void __init e820_reserve_resources_late(void)
 {
         int i;
@@ -1400,17 +1402,19 @@ void __init e820_reserve_resources_late(void)
          * avoid stolen RAM:
          */
         for (i = 0; i < e820.nr_map; i++) {
-                struct e820entry *entry = &e820_saved.map[i];
-                resource_size_t start, end;
+                struct e820entry *entry = &e820.map[i];
+                u64 start, end;
 
                 if (entry->type != E820_RAM)
                         continue;
                 start = entry->addr + entry->size;
-                end = round_up(start, ram_alignment(start));
-                if (start == end)
+                end = round_up(start, ram_alignment(start)) - 1;
+                if (end > MAX_RESOURCE_SIZE)
+                        end = MAX_RESOURCE_SIZE;
+                if (start >= end)
                         continue;
-                reserve_region_with_split(&iomem_resource, start,
-                                                  end - 1, "RAM buffer");
+                reserve_region_with_split(&iomem_resource, start, end,
+                                          "RAM buffer");
         }
 }