In the case where KASAN directly allocates memory to back vmalloc space, don't map the early shadow page over it. Not mapping the early shadow page over the whole shadow space means that there are some pgds that are not populated on boot. Allow the vmalloc fault handler to also fault in vmalloc shadow as needed. Signed-off-by: Daniel Axtens <dja@xxxxxxxxxx> --- arch/x86/Kconfig | 1 + arch/x86/mm/fault.c | 13 +++++++++++++ arch/x86/mm/kasan_init_64.c | 10 ++++++++++ 3 files changed, 24 insertions(+) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 222855cc0158..40562cc3771f 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -134,6 +134,7 @@ config X86 select HAVE_ARCH_JUMP_LABEL select HAVE_ARCH_JUMP_LABEL_RELATIVE select HAVE_ARCH_KASAN if X86_64 + select HAVE_ARCH_KASAN_VMALLOC if X86_64 select HAVE_ARCH_KGDB select HAVE_ARCH_MMAP_RND_BITS if MMU select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 6c46095cd0d9..d722230121c3 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -340,8 +340,21 @@ static noinline int vmalloc_fault(unsigned long address) pte_t *pte; /* Make sure we are in vmalloc area: */ +#ifndef CONFIG_KASAN_VMALLOC if (!(address >= VMALLOC_START && address < VMALLOC_END)) return -1; +#else + /* + * Some of the shadow mapping for the vmalloc area lives outside the + * pgds populated by kasan init. They are created dynamically and so + * we may need to fault them in. + * + * You can observe this with test_vmalloc's align_shift_alloc_test + */ + if (!((address >= VMALLOC_START && address < VMALLOC_END) || + (address >= KASAN_SHADOW_START && address < KASAN_SHADOW_END))) + return -1; +#endif /* * Copy kernel mappings over when needed. This can also diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c index 296da58f3013..e2fe1c1b805c 100644 --- a/arch/x86/mm/kasan_init_64.c +++ b/arch/x86/mm/kasan_init_64.c @@ -352,9 +352,19 @@ void __init kasan_init(void) shadow_cpu_entry_end = (void *)round_up( (unsigned long)shadow_cpu_entry_end, PAGE_SIZE); + /* + * If we're in full vmalloc mode, don't back vmalloc space with early + * shadow pages. + */ +#ifdef CONFIG_KASAN_VMALLOC + kasan_populate_early_shadow( + kasan_mem_to_shadow((void *)VMALLOC_END+1), + shadow_cpu_entry_begin); +#else kasan_populate_early_shadow( kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM), shadow_cpu_entry_begin); +#endif kasan_populate_shadow((unsigned long)shadow_cpu_entry_begin, (unsigned long)shadow_cpu_entry_end, 0); -- 2.20.1
