1 files changed, 19 insertions, 0 deletions

diff --git a/arch/x86/kernel/crash_dump_32.c b/arch/x86/kernel/crash_dump_32.c
index f7cdb3b457aa..cd97ce18c29d 100644
--- a/arch/x86/kernel/crash_dump_32.c
+++ b/arch/x86/kernel/crash_dump_32.c
@@ -16,6 +16,22 @@ static void *kdump_buf_page;
 /* Stores the physical address of elf header of crash image. */
 unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;
 
+static inline bool is_crashed_pfn_valid(unsigned long pfn)
+{
+#ifndef CONFIG_X86_PAE
+        /*
+         * non-PAE kdump kernel executed from a PAE one will crop high pte
+         * bits and poke unwanted space counting again from address 0, we
+         * don't want that. pte must fit into unsigned long. In fact the
+         * test checks high 12 bits for being zero (pfn will be shifted left
+         * by PAGE_SHIFT).
+         */
+        return pte_pfn(pfn_pte(pfn, __pgprot(0))) == pfn;
+#else
+        return true;
+#endif
+}
+
 /**
  * copy_oldmem_page - copy one page from "oldmem"
  * @pfn: page frame number to be copied
@@ -41,6 +57,9 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
         if (!csize)
                 return 0;
 
+        if (!is_crashed_pfn_valid(pfn))
+                return -EFAULT;
+
         vaddr = kmap_atomic_pfn(pfn, KM_PTE0);
 
         if (!userbuf) {