kernel/memremap, kasan: make ZONE_DEVICE with work with KASAN
authorAndrey Ryabinin <aryabinin@virtuozzo.com>
Fri, 17 Aug 2018 22:47:04 +0000 (15:47 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 17 Aug 2018 23:20:30 +0000 (16:20 -0700)
KASAN learns about hotadded memory via the memory hotplug notifier.
devm_memremap_pages() intentionally skips calling memory hotplug
notifiers.  So KASAN doesn't know anything about new memory added by
devm_memremap_pages().  This causes a crash when KASAN tries to access
non-existent shadow memory:

 BUG: unable to handle kernel paging request at ffffed0078000000
 RIP: 0010:check_memory_region+0x82/0x1e0
 Call Trace:
  memcpy+0x1f/0x50
  pmem_do_bvec+0x163/0x720
  pmem_make_request+0x305/0xac0
  generic_make_request+0x54f/0xcf0
  submit_bio+0x9c/0x370
  submit_bh_wbc+0x4c7/0x700
  block_read_full_page+0x5ef/0x870
  do_read_cache_page+0x2b8/0xb30
  read_dev_sector+0xbd/0x3f0
  read_lba.isra.0+0x277/0x670
  efi_partition+0x41a/0x18f0
  check_partition+0x30d/0x5e9
  rescan_partitions+0x18c/0x840
  __blkdev_get+0x859/0x1060
  blkdev_get+0x23f/0x810
  __device_add_disk+0x9c8/0xde0
  pmem_attach_disk+0x9a8/0xf50
  nvdimm_bus_probe+0xf3/0x3c0
  driver_probe_device+0x493/0xbd0
  bus_for_each_drv+0x118/0x1b0
  __device_attach+0x1cd/0x2b0
  bus_probe_device+0x1ac/0x260
  device_add+0x90d/0x1380
  nd_async_device_register+0xe/0x50
  async_run_entry_fn+0xc3/0x5d0
  process_one_work+0xa0a/0x1810
  worker_thread+0x87/0xe80
  kthread+0x2d7/0x390
  ret_from_fork+0x3a/0x50

Add kasan_add_zero_shadow()/kasan_remove_zero_shadow() - post mm_init()
interface to map/unmap kasan_zero_page at requested virtual addresses.
And use it to add/remove the shadow memory for hotplugged/unplugged
device memory.

Link: http://lkml.kernel.org/r/20180629164932.740-1-aryabinin@virtuozzo.com
Fixes: 41e94a851304 ("add devm_memremap_pages")
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reported-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/kasan.h
kernel/memremap.c
mm/kasan/kasan_init.c

index de784fd11d122c64691e9c2ca2db2b473074665c..46aae129917c69d2f314365281eb281c062cb609 100644 (file)
@@ -20,7 +20,7 @@ extern pmd_t kasan_zero_pmd[PTRS_PER_PMD];
 extern pud_t kasan_zero_pud[PTRS_PER_PUD];
 extern p4d_t kasan_zero_p4d[MAX_PTRS_PER_P4D];
 
-void kasan_populate_zero_shadow(const void *shadow_start,
+int kasan_populate_zero_shadow(const void *shadow_start,
                                const void *shadow_end);
 
 static inline void *kasan_mem_to_shadow(const void *addr)
@@ -71,6 +71,9 @@ struct kasan_cache {
 int kasan_module_alloc(void *addr, size_t size);
 void kasan_free_shadow(const struct vm_struct *vm);
 
+int kasan_add_zero_shadow(void *start, unsigned long size);
+void kasan_remove_zero_shadow(void *start, unsigned long size);
+
 size_t ksize(const void *);
 static inline void kasan_unpoison_slab(const void *ptr) { ksize(ptr); }
 size_t kasan_metadata_size(struct kmem_cache *cache);
@@ -124,6 +127,14 @@ static inline bool kasan_slab_free(struct kmem_cache *s, void *object,
 static inline int kasan_module_alloc(void *addr, size_t size) { return 0; }
 static inline void kasan_free_shadow(const struct vm_struct *vm) {}
 
+static inline int kasan_add_zero_shadow(void *start, unsigned long size)
+{
+       return 0;
+}
+static inline void kasan_remove_zero_shadow(void *start,
+                                       unsigned long size)
+{}
+
 static inline void kasan_unpoison_slab(const void *ptr) { }
 static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }
 
index 38283363da06d40057ddfe71c3c8ec1a2c7a94d2..1f87ea6b6545af0866baaf252380f35a2ab8c3d2 100644 (file)
@@ -5,6 +5,7 @@
 #include <linux/types.h>
 #include <linux/pfn_t.h>
 #include <linux/io.h>
+#include <linux/kasan.h>
 #include <linux/mm.h>
 #include <linux/memory_hotplug.h>
 #include <linux/swap.h>
@@ -137,6 +138,7 @@ static void devm_memremap_pages_release(void *data)
        mem_hotplug_begin();
        arch_remove_memory(align_start, align_size, pgmap->altmap_valid ?
                        &pgmap->altmap : NULL);
+       kasan_remove_zero_shadow(__va(align_start), align_size);
        mem_hotplug_done();
 
        untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
@@ -239,6 +241,12 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
                goto err_pfn_remap;
 
        mem_hotplug_begin();
+       error = kasan_add_zero_shadow(__va(align_start), align_size);
+       if (error) {
+               mem_hotplug_done();
+               goto err_kasan;
+       }
+
        error = arch_add_memory(nid, align_start, align_size, altmap, false);
        if (!error)
                move_pfn_range_to_zone(&NODE_DATA(nid)->node_zones[ZONE_DEVICE],
@@ -267,6 +275,8 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
        return __va(res->start);
 
  err_add_memory:
+       kasan_remove_zero_shadow(__va(align_start), align_size);
+ err_kasan:
        untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
  err_pfn_remap:
  err_radix:
index f436246ccc797302a38d84b669a5971e56fbb72a..7a2a2f13f86f5b604de654a7a3487ddb534d3a93 100644 (file)
 #include <linux/memblock.h>
 #include <linux/mm.h>
 #include <linux/pfn.h>
+#include <linux/slab.h>
 
 #include <asm/page.h>
 #include <asm/pgalloc.h>
 
+#include "kasan.h"
+
 /*
  * This page serves two purposes:
  *   - It used as early shadow memory. The entire shadow region populated
@@ -32,22 +35,59 @@ unsigned char kasan_zero_page[PAGE_SIZE] __page_aligned_bss;
 
 #if CONFIG_PGTABLE_LEVELS > 4
 p4d_t kasan_zero_p4d[MAX_PTRS_PER_P4D] __page_aligned_bss;
+static inline bool kasan_p4d_table(pgd_t pgd)
+{
+       return pgd_page(pgd) == virt_to_page(lm_alias(kasan_zero_p4d));
+}
+#else
+static inline bool kasan_p4d_table(pgd_t pgd)
+{
+       return 0;
+}
 #endif
 #if CONFIG_PGTABLE_LEVELS > 3
 pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
+static inline bool kasan_pud_table(p4d_t p4d)
+{
+       return p4d_page(p4d) == virt_to_page(lm_alias(kasan_zero_pud));
+}
+#else
+static inline bool kasan_pud_table(p4d_t p4d)
+{
+       return 0;
+}
 #endif
 #if CONFIG_PGTABLE_LEVELS > 2
 pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
+static inline bool kasan_pmd_table(pud_t pud)
+{
+       return pud_page(pud) == virt_to_page(lm_alias(kasan_zero_pmd));
+}
+#else
+static inline bool kasan_pmd_table(pud_t pud)
+{
+       return 0;
+}
 #endif
 pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;
 
+static inline bool kasan_pte_table(pmd_t pmd)
+{
+       return pmd_page(pmd) == virt_to_page(lm_alias(kasan_zero_pte));
+}
+
+static inline bool kasan_zero_page_entry(pte_t pte)
+{
+       return pte_page(pte) == virt_to_page(lm_alias(kasan_zero_page));
+}
+
 static __init void *early_alloc(size_t size, int node)
 {
        return memblock_virt_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS),
                                        BOOTMEM_ALLOC_ACCESSIBLE, node);
 }
 
-static void __init zero_pte_populate(pmd_t *pmd, unsigned long addr,
+static void __ref zero_pte_populate(pmd_t *pmd, unsigned long addr,
                                unsigned long end)
 {
        pte_t *pte = pte_offset_kernel(pmd, addr);
@@ -63,7 +103,7 @@ static void __init zero_pte_populate(pmd_t *pmd, unsigned long addr,
        }
 }
 
-static void __init zero_pmd_populate(pud_t *pud, unsigned long addr,
+static int __ref zero_pmd_populate(pud_t *pud, unsigned long addr,
                                unsigned long end)
 {
        pmd_t *pmd = pmd_offset(pud, addr);
@@ -78,14 +118,24 @@ static void __init zero_pmd_populate(pud_t *pud, unsigned long addr,
                }
 
                if (pmd_none(*pmd)) {
-                       pmd_populate_kernel(&init_mm, pmd,
-                                       early_alloc(PAGE_SIZE, NUMA_NO_NODE));
+                       pte_t *p;
+
+                       if (slab_is_available())
+                               p = pte_alloc_one_kernel(&init_mm, addr);
+                       else
+                               p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
+                       if (!p)
+                               return -ENOMEM;
+
+                       pmd_populate_kernel(&init_mm, pmd, p);
                }
                zero_pte_populate(pmd, addr, next);
        } while (pmd++, addr = next, addr != end);
+
+       return 0;
 }
 
-static void __init zero_pud_populate(p4d_t *p4d, unsigned long addr,
+static int __ref zero_pud_populate(p4d_t *p4d, unsigned long addr,
                                unsigned long end)
 {
        pud_t *pud = pud_offset(p4d, addr);
@@ -103,14 +153,24 @@ static void __init zero_pud_populate(p4d_t *p4d, unsigned long addr,
                }
 
                if (pud_none(*pud)) {
-                       pud_populate(&init_mm, pud,
-                               early_alloc(PAGE_SIZE, NUMA_NO_NODE));
+                       pmd_t *p;
+
+                       if (slab_is_available()) {
+                               p = pmd_alloc(&init_mm, pud, addr);
+                               if (!p)
+                                       return -ENOMEM;
+                       } else {
+                               pud_populate(&init_mm, pud,
+                                       early_alloc(PAGE_SIZE, NUMA_NO_NODE));
+                       }
                }
                zero_pmd_populate(pud, addr, next);
        } while (pud++, addr = next, addr != end);
+
+       return 0;
 }
 
-static void __init zero_p4d_populate(pgd_t *pgd, unsigned long addr,
+static int __ref zero_p4d_populate(pgd_t *pgd, unsigned long addr,
                                unsigned long end)
 {
        p4d_t *p4d = p4d_offset(pgd, addr);
@@ -132,11 +192,21 @@ static void __init zero_p4d_populate(pgd_t *pgd, unsigned long addr,
                }
 
                if (p4d_none(*p4d)) {
-                       p4d_populate(&init_mm, p4d,
-                               early_alloc(PAGE_SIZE, NUMA_NO_NODE));
+                       pud_t *p;
+
+                       if (slab_is_available()) {
+                               p = pud_alloc(&init_mm, p4d, addr);
+                               if (!p)
+                                       return -ENOMEM;
+                       } else {
+                               p4d_populate(&init_mm, p4d,
+                                       early_alloc(PAGE_SIZE, NUMA_NO_NODE));
+                       }
                }
                zero_pud_populate(p4d, addr, next);
        } while (p4d++, addr = next, addr != end);
+
+       return 0;
 }
 
 /**
@@ -145,7 +215,7 @@ static void __init zero_p4d_populate(pgd_t *pgd, unsigned long addr,
  * @shadow_start - start of the memory range to populate
  * @shadow_end   - end of the memory range to populate
  */
-void __init kasan_populate_zero_shadow(const void *shadow_start,
+int __ref kasan_populate_zero_shadow(const void *shadow_start,
                                const void *shadow_end)
 {
        unsigned long addr = (unsigned long)shadow_start;
@@ -191,9 +261,229 @@ void __init kasan_populate_zero_shadow(const void *shadow_start,
                }
 
                if (pgd_none(*pgd)) {
-                       pgd_populate(&init_mm, pgd,
-                               early_alloc(PAGE_SIZE, NUMA_NO_NODE));
+                       p4d_t *p;
+
+                       if (slab_is_available()) {
+                               p = p4d_alloc(&init_mm, pgd, addr);
+                               if (!p)
+                                       return -ENOMEM;
+                       } else {
+                               pgd_populate(&init_mm, pgd,
+                                       early_alloc(PAGE_SIZE, NUMA_NO_NODE));
+                       }
                }
                zero_p4d_populate(pgd, addr, next);
        } while (pgd++, addr = next, addr != end);
+
+       return 0;
+}
+
+static void kasan_free_pte(pte_t *pte_start, pmd_t *pmd)
+{
+       pte_t *pte;
+       int i;
+
+       for (i = 0; i < PTRS_PER_PTE; i++) {
+               pte = pte_start + i;
+               if (!pte_none(*pte))
+                       return;
+       }
+
+       pte_free_kernel(&init_mm, (pte_t *)page_to_virt(pmd_page(*pmd)));
+       pmd_clear(pmd);
+}
+
+static void kasan_free_pmd(pmd_t *pmd_start, pud_t *pud)
+{
+       pmd_t *pmd;
+       int i;
+
+       for (i = 0; i < PTRS_PER_PMD; i++) {
+               pmd = pmd_start + i;
+               if (!pmd_none(*pmd))
+                       return;
+       }
+
+       pmd_free(&init_mm, (pmd_t *)page_to_virt(pud_page(*pud)));
+       pud_clear(pud);
+}
+
+static void kasan_free_pud(pud_t *pud_start, p4d_t *p4d)
+{
+       pud_t *pud;
+       int i;
+
+       for (i = 0; i < PTRS_PER_PUD; i++) {
+               pud = pud_start + i;
+               if (!pud_none(*pud))
+                       return;
+       }
+
+       pud_free(&init_mm, (pud_t *)page_to_virt(p4d_page(*p4d)));
+       p4d_clear(p4d);
+}
+
+static void kasan_free_p4d(p4d_t *p4d_start, pgd_t *pgd)
+{
+       p4d_t *p4d;
+       int i;
+
+       for (i = 0; i < PTRS_PER_P4D; i++) {
+               p4d = p4d_start + i;
+               if (!p4d_none(*p4d))
+                       return;
+       }
+
+       p4d_free(&init_mm, (p4d_t *)page_to_virt(pgd_page(*pgd)));
+       pgd_clear(pgd);
+}
+
+static void kasan_remove_pte_table(pte_t *pte, unsigned long addr,
+                               unsigned long end)
+{
+       unsigned long next;
+
+       for (; addr < end; addr = next, pte++) {
+               next = (addr + PAGE_SIZE) & PAGE_MASK;
+               if (next > end)
+                       next = end;
+
+               if (!pte_present(*pte))
+                       continue;
+
+               if (WARN_ON(!kasan_zero_page_entry(*pte)))
+                       continue;
+               pte_clear(&init_mm, addr, pte);
+       }
+}
+
+static void kasan_remove_pmd_table(pmd_t *pmd, unsigned long addr,
+                               unsigned long end)
+{
+       unsigned long next;
+
+       for (; addr < end; addr = next, pmd++) {
+               pte_t *pte;
+
+               next = pmd_addr_end(addr, end);
+
+               if (!pmd_present(*pmd))
+                       continue;
+
+               if (kasan_pte_table(*pmd)) {
+                       if (IS_ALIGNED(addr, PMD_SIZE) &&
+                           IS_ALIGNED(next, PMD_SIZE))
+                               pmd_clear(pmd);
+                       continue;
+               }
+               pte = pte_offset_kernel(pmd, addr);
+               kasan_remove_pte_table(pte, addr, next);
+               kasan_free_pte(pte_offset_kernel(pmd, 0), pmd);
+       }
+}
+
+static void kasan_remove_pud_table(pud_t *pud, unsigned long addr,
+                               unsigned long end)
+{
+       unsigned long next;
+
+       for (; addr < end; addr = next, pud++) {
+               pmd_t *pmd, *pmd_base;
+
+               next = pud_addr_end(addr, end);
+
+               if (!pud_present(*pud))
+                       continue;
+
+               if (kasan_pmd_table(*pud)) {
+                       if (IS_ALIGNED(addr, PUD_SIZE) &&
+                           IS_ALIGNED(next, PUD_SIZE))
+                               pud_clear(pud);
+                       continue;
+               }
+               pmd = pmd_offset(pud, addr);
+               pmd_base = pmd_offset(pud, 0);
+               kasan_remove_pmd_table(pmd, addr, next);
+               kasan_free_pmd(pmd_base, pud);
+       }
+}
+
+static void kasan_remove_p4d_table(p4d_t *p4d, unsigned long addr,
+                               unsigned long end)
+{
+       unsigned long next;
+
+       for (; addr < end; addr = next, p4d++) {
+               pud_t *pud;
+
+               next = p4d_addr_end(addr, end);
+
+               if (!p4d_present(*p4d))
+                       continue;
+
+               if (kasan_pud_table(*p4d)) {
+                       if (IS_ALIGNED(addr, P4D_SIZE) &&
+                           IS_ALIGNED(next, P4D_SIZE))
+                               p4d_clear(p4d);
+                       continue;
+               }
+               pud = pud_offset(p4d, addr);
+               kasan_remove_pud_table(pud, addr, next);
+               kasan_free_pud(pud_offset(p4d, 0), p4d);
+       }
+}
+
+void kasan_remove_zero_shadow(void *start, unsigned long size)
+{
+       unsigned long addr, end, next;
+       pgd_t *pgd;
+
+       addr = (unsigned long)kasan_mem_to_shadow(start);
+       end = addr + (size >> KASAN_SHADOW_SCALE_SHIFT);
+
+       if (WARN_ON((unsigned long)start %
+                       (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)) ||
+           WARN_ON(size % (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)))
+               return;
+
+       for (; addr < end; addr = next) {
+               p4d_t *p4d;
+
+               next = pgd_addr_end(addr, end);
+
+               pgd = pgd_offset_k(addr);
+               if (!pgd_present(*pgd))
+                       continue;
+
+               if (kasan_p4d_table(*pgd)) {
+                       if (IS_ALIGNED(addr, PGDIR_SIZE) &&
+                           IS_ALIGNED(next, PGDIR_SIZE))
+                               pgd_clear(pgd);
+                       continue;
+               }
+
+               p4d = p4d_offset(pgd, addr);
+               kasan_remove_p4d_table(p4d, addr, next);
+               kasan_free_p4d(p4d_offset(pgd, 0), pgd);
+       }
+}
+
+int kasan_add_zero_shadow(void *start, unsigned long size)
+{
+       int ret;
+       void *shadow_start, *shadow_end;
+
+       shadow_start = kasan_mem_to_shadow(start);
+       shadow_end = shadow_start + (size >> KASAN_SHADOW_SCALE_SHIFT);
+
+       if (WARN_ON((unsigned long)start %
+                       (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)) ||
+           WARN_ON(size % (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)))
+               return -EINVAL;
+
+       ret = kasan_populate_zero_shadow(shadow_start, shadow_end);
+       if (ret)
+               kasan_remove_zero_shadow(shadow_start,
+                                       size >> KASAN_SHADOW_SCALE_SHIFT);
+       return ret;
 }