Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input

[sfrench/cifs-2.6.git] / arch / x86 / kernel / crash_dump_32.c

diff --git a/arch/x86/kernel/crash_dump_32.c b/arch/x86/kernel/crash_dump_32.c
index f7cdb3b457aadc7f0f8951323dc507827211be75..cd97ce18c29d10e27e6c9f0421f1492137a313e6 100644 (file)
--- 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) {