Commit beb564bc authored by Andrey Ryabinin's avatar Andrey Ryabinin Committed by Jialin Zhang
Browse files

x86/kasan: Map shadow for percpu pages on demand 

mainline inclusion
from mainline-v6.2-rc1
commit 3f148f33
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I6C6UC
CVE: CVE-2023-0597

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3f148f3318140035e87decc1214795ff0755757b



--------------------------------

KASAN maps shadow for the entire CPU-entry-area:
  [CPU_ENTRY_AREA_BASE, CPU_ENTRY_AREA_BASE + CPU_ENTRY_AREA_MAP_SIZE]

This will explode once the per-cpu entry areas are randomized since it
will increase CPU_ENTRY_AREA_MAP_SIZE to 512 GB and KASAN fails to
allocate shadow for such big area.

Fix this by allocating KASAN shadow only for really used cpu entry area
addresses mapped by cea_map_percpu_pages()

Thanks to the 0day folks for finding and reporting this to be an issue.

[ dhansen: tweak changelog since this will get committed before peterz's
	   actual cpu-entry-area randomization ]

Signed-off-by: default avatarAndrey Ryabinin <ryabinin.a.a@gmail.com>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Tested-by: default avatarYujie Liu <yujie.liu@intel.com>
Cc: kernel test robot <yujie.liu@intel.com>
Link: https://lore.kernel.org/r/202210241508.2e203c3d-yujie.liu@intel.com


Signed-off-by: default avatarTong Tiangen <tongtiangen@huawei.com>
Reviewed-by: default avatarWang Weiyang <wangweiyang2@huawei.com>
Reviewed-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: default avatarJialin Zhang <zhangjialin11@huawei.com>
parent f0153f08

arch/x86/include/asm/kasan.h

+3 −0
Original line number Diff line number Diff line
@@ -28,9 +28,12 @@ 
#ifdef CONFIG_KASAN

void __init kasan_early_init(void);

void __init kasan_init(void);

void __init kasan_populate_shadow_for_vaddr(void *va, size_t size, int nid);

#else

static inline void kasan_early_init(void) { }

static inline void kasan_init(void) { }

static inline void kasan_populate_shadow_for_vaddr(void *va, size_t size,

						   int nid) { }

#endif



#endif

arch/x86/mm/cpu_entry_area.c

+7 −1
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
#include <asm/cpu_entry_area.h>

#include <asm/fixmap.h>

#include <asm/desc.h>

#include <asm/kasan.h>



static DEFINE_PER_CPU_PAGE_ALIGNED(struct entry_stack_page, entry_stack_storage);
@@ -95,8 +96,13 @@ void cea_set_pte(void *cea_vaddr, phys_addr_t pa, pgprot_t flags) 
static void __init

cea_map_percpu_pages(void *cea_vaddr, void *ptr, int pages, pgprot_t prot)

{

	phys_addr_t pa = per_cpu_ptr_to_phys(ptr);



	kasan_populate_shadow_for_vaddr(cea_vaddr, pages * PAGE_SIZE,

					early_pfn_to_nid(PFN_DOWN(pa)));



	for ( ; pages; pages--, cea_vaddr+= PAGE_SIZE, ptr += PAGE_SIZE)

		cea_set_pte(cea_vaddr, per_cpu_ptr_to_phys(ptr), prot);

		cea_set_pte(cea_vaddr, pa, prot);

}



static void __init percpu_setup_debug_store(unsigned int cpu)

arch/x86/mm/kasan_init_64.c

+12 −3
Original line number Diff line number Diff line
@@ -318,6 +318,18 @@ void __init kasan_early_init(void) 
	kasan_map_early_shadow(init_top_pgt);

}



void __init kasan_populate_shadow_for_vaddr(void *va, size_t size, int nid)

{

	unsigned long shadow_start, shadow_end;



	shadow_start = (unsigned long)kasan_mem_to_shadow(va);

	shadow_start = round_down(shadow_start, PAGE_SIZE);

	shadow_end = (unsigned long)kasan_mem_to_shadow(va + size);

	shadow_end = round_up(shadow_end, PAGE_SIZE);



	kasan_populate_shadow(shadow_start, shadow_end, nid);

}



void __init kasan_init(void)

{

	int i;
@@ -395,9 +407,6 @@ void __init kasan_init(void) 
		kasan_mem_to_shadow((void *)VMALLOC_END + 1),

		shadow_cpu_entry_begin);



	kasan_populate_shadow((unsigned long)shadow_cpu_entry_begin,

			      (unsigned long)shadow_cpu_entry_end, 0);



	kasan_populate_early_shadow(shadow_cpu_entry_end,

			kasan_mem_to_shadow((void *)__START_KERNEL_map));