On 29.08.25 21:07, Kees Cook wrote:
Seen during KPTI initialization:
CFI failure at create_kpti_ng_temp_pgd+0x124/0xce8 (target:
kpti_ng_pgd_alloc+0x0/0x14; expected type: 0xd61b88b6)
The call site is alloc_init_pud() at arch/arm64/mm/mmu.c:
pud_phys = pgtable_alloc(TABLE_PUD);
alloc_init_pud() has the prototype:
static void alloc_init_pud(p4d_t *p4dp, unsigned long addr, unsigned long
end,
phys_addr_t phys, pgprot_t prot,
phys_addr_t (*pgtable_alloc)(enum pgtable_type),
int flags)
where the pgtable_alloc() prototype is declared.
The target (kpti_ng_pgd_alloc) is used in arch/arm64/kernel/cpufeature.c:
create_kpti_ng_temp_pgd(kpti_ng_temp_pgd, __pa(alloc), KPTI_NG_TEMP_VA,
PAGE_SIZE, PAGE_KERNEL, kpti_ng_pgd_alloc, 0);
which is an alias for __create_pgd_mapping_locked() with prototype:
extern __alias(__create_pgd_mapping_locked)
void create_kpti_ng_temp_pgd(pgd_t *pgdir, phys_addr_t phys,
unsigned long virt,
phys_addr_t size, pgprot_t prot,
phys_addr_t (*pgtable_alloc)(enum pgtable_type),
int flags);
__create_pgd_mapping_locked() passes the function pointer down:
__create_pgd_mapping_locked() -> alloc_init_p4d() -> alloc_init_pud()
But the target function (kpti_ng_pgd_alloc) has the wrong signature:
static phys_addr_t __init kpti_ng_pgd_alloc(int shift);
The "int" should be "enum pgtable_type".
To make "enum pgtable_type" available to cpufeature.c, move
enum pgtable_type definition from arch/arm64/mm/mmu.c to
arch/arm64/include/asm/mmu.h.
Adjust kpti_ng_pgd_alloc to use "enum pgtable_type" instead of "int".
The function behavior remains identical (parameter is unused).
Fixes: c64f46ee1377 ("arm64: mm: use enum to identify pgtable level instead of
*_SHIFT")
Signed-off-by: Kees Cook <[email protected]>
---
v2: Fixed the Fixes line. ;)
v1: https://lore.kernel.org/lkml/[email protected]/
Cc: Kevin Brodsky <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Oliver Upton <[email protected]>
Cc: Yue Haibing <[email protected]>
Cc: Marc Zyngier <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: <[email protected]>
---
arch/arm64/include/asm/mmu.h | 7 +++++++
arch/arm64/kernel/cpufeature.c | 5 +++--
arch/arm64/mm/mmu.c | 7 -------
3 files changed, 10 insertions(+), 9 deletions(-)
diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
index 6e8aa8e72601..49f1a810df16 100644
--- a/arch/arm64/include/asm/mmu.h
+++ b/arch/arm64/include/asm/mmu.h
@@ -17,6 +17,13 @@
#include <linux/refcount.h>
#include <asm/cpufeature.h>
+enum pgtable_type {
+ TABLE_PTE,
+ TABLE_PMD,
+ TABLE_PUD,
+ TABLE_P4D,
+};
Just noting that we now have "enum pgtable_level" in
include/linux/pgtable.h that could at some point possibly be used here
instead (not in this fix).
--
Cheers
David / dhildenb
