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-rw-r--r--arch/x86/kernel/crash_dump_32.c19
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) {