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kasan: fix crashes on access to memory mapped by vm_map_ram() 

With CONFIG_KASAN_VMALLOC=y any use of memory obtained via vm_map_ram()
will crash because there is no shadow backing that memory.

Instead of sprinkling additional kasan_populate_vmalloc() calls all over
the vmalloc code, move it into alloc_vmap_area(). This will fix
vm_map_ram() and simplify the code a bit.

[aryabinin@virtuozzo.com: v2]
  Link: http://lkml.kernel.org/r/20191205095942.1761-1-aryabinin@virtuozzo.comLink: http://lkml.kernel.org/r/20191204204534.32202-1-aryabinin@virtuozzo.com
Fixes: 3c5c3cfb9e ("kasan: support backing vmalloc space with real shadow memory")
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Daniel Axtens <dja@axtens.net>
Cc: Alexander Potapenko <glider@google.com>
Cc: Daniel Axtens <dja@axtens.net>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrey Ryabinin 2019-12-17 20:51:38 -08:00 committed by Linus Torvalds
parent 2187f215eb
commit d98c9e83b5
3 changed files with 67 additions and 60 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
include/linux/kasan.h
View File

@ -205,20 +205,23 @@ static inline void *kasan_reset_tag(const void *addr)
#endif /* CONFIG_KASAN_SW_TAGS */
#ifdef CONFIG_KASAN_VMALLOC
int kasan_populate_vmalloc(unsigned long requested_size,
struct vm_struct *area);
void kasan_poison_vmalloc(void *start, unsigned long size);
int kasan_populate_vmalloc(unsigned long addr, unsigned long size);
void kasan_poison_vmalloc(const void *start, unsigned long size);
void kasan_unpoison_vmalloc(const void *start, unsigned long size);
void kasan_release_vmalloc(unsigned long start, unsigned long end,
unsigned long free_region_start,
unsigned long free_region_end);
#else
static inline int kasan_populate_vmalloc(unsigned long requested_size,
struct vm_struct *area)
static inline int kasan_populate_vmalloc(unsigned long start,
unsigned long size)
{
return 0;
}
static inline void kasan_poison_vmalloc(void *start, unsigned long size) {}
static inline void kasan_poison_vmalloc(const void *start, unsigned long size)
{ }
static inline void kasan_unpoison_vmalloc(const void *start, unsigned long size)
{ }
static inline void kasan_release_vmalloc(unsigned long start,
unsigned long end,
unsigned long free_region_start,

27
mm/kasan/common.c
View File

@ -778,15 +778,17 @@ static int kasan_populate_vmalloc_pte(pte_t *ptep, unsigned long addr,
return 0;
}
int kasan_populate_vmalloc(unsigned long requested_size, struct vm_struct *area)
int kasan_populate_vmalloc(unsigned long addr, unsigned long size)
{
unsigned long shadow_start, shadow_end;
int ret;
shadow_start = (unsigned long)kasan_mem_to_shadow(area->addr);
if (!is_vmalloc_or_module_addr((void *)addr))
return 0;
shadow_start = (unsigned long)kasan_mem_to_shadow((void *)addr);
shadow_start = ALIGN_DOWN(shadow_start, PAGE_SIZE);
shadow_end = (unsigned long)kasan_mem_to_shadow(area->addr +
area->size);
shadow_end = (unsigned long)kasan_mem_to_shadow((void *)addr + size);
shadow_end = ALIGN(shadow_end, PAGE_SIZE);
ret = apply_to_page_range(&init_mm, shadow_start,
@ -797,10 +799,6 @@ int kasan_populate_vmalloc(unsigned long requested_size, struct vm_struct *area)
flush_cache_vmap(shadow_start, shadow_end);
kasan_unpoison_shadow(area->addr, requested_size);
area->flags |= VM_KASAN;
/*
* We need to be careful about inter-cpu effects here. Consider:
*
@ -843,12 +841,23 @@ int kasan_populate_vmalloc(unsigned long requested_size, struct vm_struct *area)
* Poison the shadow for a vmalloc region. Called as part of the
* freeing process at the time the region is freed.
*/
void kasan_poison_vmalloc(void *start, unsigned long size)
void kasan_poison_vmalloc(const void *start, unsigned long size)
{
if (!is_vmalloc_or_module_addr(start))
return;
size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
kasan_poison_shadow(start, size, KASAN_VMALLOC_INVALID);
}
void kasan_unpoison_vmalloc(const void *start, unsigned long size)
{
if (!is_vmalloc_or_module_addr(start))
return;
kasan_unpoison_shadow(start, size);
}
static int kasan_depopulate_vmalloc_pte(pte_t *ptep, unsigned long addr,
void *unused)
{

85
mm/vmalloc.c
View File

@ -1061,6 +1061,26 @@ __alloc_vmap_area(unsigned long size, unsigned long align,
return nva_start_addr;
}
/*
* Free a region of KVA allocated by alloc_vmap_area
*/
static void free_vmap_area(struct vmap_area *va)
{
/*
* Remove from the busy tree/list.
*/
spin_lock(&vmap_area_lock);
unlink_va(va, &vmap_area_root);
spin_unlock(&vmap_area_lock);
/*
* Insert/Merge it back to the free tree/list.
*/
spin_lock(&free_vmap_area_lock);
merge_or_add_vmap_area(va, &free_vmap_area_root, &free_vmap_area_list);
spin_unlock(&free_vmap_area_lock);
}
/*
* Allocate a region of KVA of the specified size and alignment, within the
* vstart and vend.
@ -1073,6 +1093,7 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
struct vmap_area *va, *pva;
unsigned long addr;
int purged = 0;
int ret;
BUG_ON(!size);
BUG_ON(offset_in_page(size));
@ -1139,6 +1160,7 @@ retry:
va->va_end = addr + size;
va->vm = NULL;
spin_lock(&vmap_area_lock);
insert_vmap_area(va, &vmap_area_root, &vmap_area_list);
spin_unlock(&vmap_area_lock);
@ -1147,6 +1169,12 @@ retry:
BUG_ON(va->va_start < vstart);
BUG_ON(va->va_end > vend);
ret = kasan_populate_vmalloc(addr, size);
if (ret) {
free_vmap_area(va);
return ERR_PTR(ret);
}
return va;
overflow:
@ -1185,26 +1213,6 @@ int unregister_vmap_purge_notifier(struct notifier_block *nb)
}
EXPORT_SYMBOL_GPL(unregister_vmap_purge_notifier);
/*
* Free a region of KVA allocated by alloc_vmap_area
*/
static void free_vmap_area(struct vmap_area *va)
{
/*
* Remove from the busy tree/list.
*/
spin_lock(&vmap_area_lock);
unlink_va(va, &vmap_area_root);
spin_unlock(&vmap_area_lock);
/*
* Insert/Merge it back to the free tree/list.
*/
spin_lock(&free_vmap_area_lock);
merge_or_add_vmap_area(va, &free_vmap_area_root, &free_vmap_area_list);
spin_unlock(&free_vmap_area_lock);
}
/*
* Clear the pagetable entries of a given vmap_area
*/
@ -1771,6 +1779,8 @@ void vm_unmap_ram(const void *mem, unsigned int count)
BUG_ON(addr > VMALLOC_END);
BUG_ON(!PAGE_ALIGNED(addr));
kasan_poison_vmalloc(mem, size);
if (likely(count <= VMAP_MAX_ALLOC)) {
debug_check_no_locks_freed(mem, size);
vb_free(mem, size);
@ -1821,6 +1831,9 @@ void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t pro
addr = va->va_start;
mem = (void *)addr;
}
kasan_unpoison_vmalloc(mem, size);
if (vmap_page_range(addr, addr + size, prot, pages) < 0) {
vm_unmap_ram(mem, count);
return NULL;
@ -2075,6 +2088,7 @@ static struct vm_struct *__get_vm_area_node(unsigned long size,
{
struct vmap_area *va;
struct vm_struct *area;
unsigned long requested_size = size;
BUG_ON(in_interrupt());
size = PAGE_ALIGN(size);
@ -2098,23 +2112,9 @@ static struct vm_struct *__get_vm_area_node(unsigned long size,
return NULL;
}
setup_vmalloc_vm(area, va, flags, caller);
kasan_unpoison_vmalloc((void *)va->va_start, requested_size);
/*
* For KASAN, if we are in vmalloc space, we need to cover the shadow
* area with real memory. If we come here through VM_ALLOC, this is
* done by a higher level function that has access to the true size,
* which might not be a full page.
*
* We assume module space comes via VM_ALLOC path.
*/
if (is_vmalloc_addr(area->addr) && !(area->flags & VM_ALLOC)) {
if (kasan_populate_vmalloc(area->size, area)) {
unmap_vmap_area(va);
kfree(area);
return NULL;
}
}
setup_vmalloc_vm(area, va, flags, caller);
return area;
}
@ -2293,8 +2293,7 @@ static void __vunmap(const void *addr, int deallocate_pages)
debug_check_no_locks_freed(area->addr, get_vm_area_size(area));
debug_check_no_obj_freed(area->addr, get_vm_area_size(area));
if (area->flags & VM_KASAN)
kasan_poison_vmalloc(area->addr, area->size);
kasan_poison_vmalloc(area->addr, area->size);
vm_remove_mappings(area, deallocate_pages);
@ -2539,7 +2538,7 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
if (!size || (size >> PAGE_SHIFT) > totalram_pages())
goto fail;
area = __get_vm_area_node(size, align, VM_ALLOC | VM_UNINITIALIZED |
area = __get_vm_area_node(real_size, align, VM_ALLOC | VM_UNINITIALIZED |
vm_flags, start, end, node, gfp_mask, caller);
if (!area)
goto fail;
@ -2548,11 +2547,6 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
if (!addr)
return NULL;
if (is_vmalloc_or_module_addr(area->addr)) {
if (kasan_populate_vmalloc(real_size, area))
return NULL;
}
/*
* In this function, newly allocated vm_struct has VM_UNINITIALIZED
* flag. It means that vm_struct is not fully initialized.
@ -3437,7 +3431,8 @@ retry:
/* populate the shadow space outside of the lock */
for (area = 0; area < nr_vms; area++) {
/* assume success here */
kasan_populate_vmalloc(sizes[area], vms[area]);
kasan_populate_vmalloc(vas[area]->va_start, sizes[area]);
kasan_unpoison_vmalloc((void *)vms[area]->addr, sizes[area]);
}
kfree(vas);