From ceca927c86e6f72f72d45487a34368bc9509431d Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Fri, 29 Aug 2025 12:07:25 -0700 Subject: [PATCH] arm64: mm: Fix CFI failure due to kpti_ng_pgd_alloc function signature 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") Cc: # 6.16.x Signed-off-by: Kees Cook Acked-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20250829190721.it.373-kees@kernel.org Reviewed-by: Ryan Roberts Signed-off-by: Catalin Marinas --- 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 #include +enum pgtable_type { + TABLE_PTE, + TABLE_PMD, + TABLE_PUD, + TABLE_P4D, +}; + typedef struct { atomic64_t id; #ifdef CONFIG_COMPAT diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 9ad065f15f1d..e49d142a281f 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -84,6 +84,7 @@ #include #include #include +#include #include #include #include @@ -1945,11 +1946,11 @@ static bool has_pmuv3(const struct arm64_cpu_capabilities *entry, int scope) extern 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)(int), int flags); + phys_addr_t (*pgtable_alloc)(enum pgtable_type), int flags); static phys_addr_t __initdata kpti_ng_temp_alloc; -static phys_addr_t __init kpti_ng_pgd_alloc(int shift) +static phys_addr_t __init kpti_ng_pgd_alloc(enum pgtable_type type) { kpti_ng_temp_alloc -= PAGE_SIZE; return kpti_ng_temp_alloc; diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 34e5d78af076..183801520740 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -47,13 +47,6 @@ #define NO_CONT_MAPPINGS BIT(1) #define NO_EXEC_MAPPINGS BIT(2) /* assumes FEAT_HPDS is not used */ -enum pgtable_type { - TABLE_PTE, - TABLE_PMD, - TABLE_PUD, - TABLE_P4D, -}; - u64 kimage_voffset __ro_after_init; EXPORT_SYMBOL(kimage_voffset); -- 2.25.1