6.11-stable review patch. If anyone has any objections, please let me know.
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From: Huacai Chen chenhuacai@loongson.cn
commit 227ca9f6f6aeb8aa8f0c10430b955f1fe2aeab91 upstream.
If PGDIR_SIZE is too large for cpu_vabits, KASAN_SHADOW_END will overflow UINTPTR_MAX because KASAN_SHADOW_START/KASAN_SHADOW_END are aligned up by PGDIR_SIZE. And then the overflowed KASAN_SHADOW_END looks like a user space address.
For example, PGDIR_SIZE of CONFIG_4KB_4LEVEL is 2^39, which is too large for Loongson-2K series whose cpu_vabits = 39.
Since CONFIG_4KB_4LEVEL is completely legal for CPUs with cpu_vabits <= 39, we just disable KASAN via early return in kasan_init(). Otherwise we get a boot failure.
Moreover, we change KASAN_SHADOW_END from the first address after KASAN shadow area to the last address in KASAN shadow area, in order to avoid the end address exactly overflow to 0 (which is a legal case). We don't need to worry about alignment because pgd_addr_end() can handle it.
Cc: stable@vger.kernel.org Reviewed-by: Jiaxun Yang jiaxun.yang@flygoat.com Signed-off-by: Huacai Chen chenhuacai@loongson.cn Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/loongarch/include/asm/kasan.h | 2 +- arch/loongarch/mm/kasan_init.c | 15 +++++++++++++-- 2 files changed, 14 insertions(+), 3 deletions(-)
--- a/arch/loongarch/include/asm/kasan.h +++ b/arch/loongarch/include/asm/kasan.h @@ -51,7 +51,7 @@ /* KAsan shadow memory start right after vmalloc. */ #define KASAN_SHADOW_START round_up(KFENCE_AREA_END, PGDIR_SIZE) #define KASAN_SHADOW_SIZE (XKVRANGE_VC_SHADOW_END - XKPRANGE_CC_KASAN_OFFSET) -#define KASAN_SHADOW_END round_up(KASAN_SHADOW_START + KASAN_SHADOW_SIZE, PGDIR_SIZE) +#define KASAN_SHADOW_END (round_up(KASAN_SHADOW_START + KASAN_SHADOW_SIZE, PGDIR_SIZE) - 1)
#define XKPRANGE_CC_SHADOW_OFFSET (KASAN_SHADOW_START + XKPRANGE_CC_KASAN_OFFSET) #define XKPRANGE_UC_SHADOW_OFFSET (KASAN_SHADOW_START + XKPRANGE_UC_KASAN_OFFSET) --- a/arch/loongarch/mm/kasan_init.c +++ b/arch/loongarch/mm/kasan_init.c @@ -218,7 +218,7 @@ static void __init kasan_map_populate(un asmlinkage void __init kasan_early_init(void) { BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE)); - BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE)); + BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END + 1, PGDIR_SIZE)); }
static inline void kasan_set_pgd(pgd_t *pgdp, pgd_t pgdval) @@ -233,7 +233,7 @@ static void __init clear_pgds(unsigned l * swapper_pg_dir. pgd_clear() can't be used * here because it's nop on 2,3-level pagetable setups */ - for (; start < end; start += PGDIR_SIZE) + for (; start < end; start = pgd_addr_end(start, end)) kasan_set_pgd((pgd_t *)pgd_offset_k(start), __pgd(0)); }
@@ -243,6 +243,17 @@ void __init kasan_init(void) phys_addr_t pa_start, pa_end;
/* + * If PGDIR_SIZE is too large for cpu_vabits, KASAN_SHADOW_END will + * overflow UINTPTR_MAX and then looks like a user space address. + * For example, PGDIR_SIZE of CONFIG_4KB_4LEVEL is 2^39, which is too + * large for Loongson-2K series whose cpu_vabits = 39. + */ + if (KASAN_SHADOW_END < vm_map_base) { + pr_warn("PGDIR_SIZE too large for cpu_vabits, KernelAddressSanitizer disabled.\n"); + return; + } + + /* * PGD was populated as invalid_pmd_table or invalid_pud_table * in pagetable_init() which depends on how many levels of page * table you are using, but we had to clean the gpd of kasan