x86/mm: Use the correct function type for native_set_fixmap()

We call native_set_fixmap indirectly through the function pointer
struct pv_mmu_ops::set_fixmap, which expects the first parameter to be
'unsigned' instead of 'enum fixed_addresses'. This patch changes the
function type for native_set_fixmap to match the pointer, which fixes
indirect call mismatches with Control-Flow Integrity (CFI) checking.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H . Peter Anvin <hpa@zytor.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190913211402.193018-1-samitolvanen@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
index 0c47aa8..28183ee 100644 (file)
--- a/arch/x86/include/asm/fixmap.h
+++ b/arch/x86/include/asm/fixmap.h
@@ -156,7 +156,7 @@ extern pte_t *kmap_pte;
 extern pte_t *pkmap_page_table;
 
 void __native_set_fixmap(enum fixed_addresses idx, pte_t pte);
-void native_set_fixmap(enum fixed_addresses idx,
+void native_set_fixmap(unsigned /* enum fixed_addresses */ idx,
                       phys_addr_t phys, pgprot_t flags);
 
 #ifndef CONFIG_PARAVIRT_XXL

diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 3e4b903..7bd2c3a 100644 (file)
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -643,8 +643,8 @@ void __native_set_fixmap(enum fixed_addresses idx, pte_t pte)
        fixmaps_set++;
 }
 
-void native_set_fixmap(enum fixed_addresses idx, phys_addr_t phys,
-                      pgprot_t flags)
+void native_set_fixmap(unsigned /* enum fixed_addresses */ idx,
+                      phys_addr_t phys, pgprot_t flags)
 {
        /* Sanitize 'prot' against any unsupported bits: */
        pgprot_val(flags) &= __default_kernel_pte_mask;