The patch titled
Subject: kasan: fix crashes on access to memory mapped by vm_map_ram()
has been added to the -mm tree. Its filename is
kasan-fix-crashes-on-access-to-memory-mapped-by-vm_map_ram.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kasan-fix-crashes-on-access-to-memory-mapped-by-vm_map_ram.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kasan-fix-crashes-on-access-to-memory-mapped-by-vm_map_ram.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Subject: 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.
Link: http://lkml.kernel.org/r/20191204204534.32202-1-aryabinin@xxxxxxxxxxxxx
Fixes: 3c5c3cfb9ef4 ("kasan: support backing vmalloc space with real shadow memory")
Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Reported-by: syzbot+82e323920b78d54aaed5@xxxxxxxxxxxxxxxxxxxxxxxxx
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Daniel Axtens <dja@xxxxxxxxxx>
Cc: Qian Cai <cai@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/kasan.h | 15 ++++++++-----
mm/kasan/common.c | 27 ++++++++++++++++--------
mm/vmalloc.c | 45 ++++++++++++++++------------------------
3 files changed, 46 insertions(+), 41 deletions(-)
--- a/include/linux/kasan.h~kasan-fix-crashes-on-access-to-memory-mapped-by-vm_map_ram
+++ a/include/linux/kasan.h
@@ -205,20 +205,23 @@ static inline void *kasan_reset_tag(cons
#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,
--- a/mm/kasan/common.c~kasan-fix-crashes-on-access-to-memory-mapped-by-vm_map_ram
+++ a/mm/kasan/common.c
@@ -778,15 +778,17 @@ static int kasan_populate_vmalloc_pte(pt
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
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
* 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)
{
--- a/mm/vmalloc.c~kasan-fix-crashes-on-access-to-memory-mapped-by-vm_map_ram
+++ a/mm/vmalloc.c
@@ -1073,6 +1073,7 @@ static struct vmap_area *alloc_vmap_area
struct vmap_area *va, *pva;
unsigned long addr;
int purged = 0;
+ int ret = -EBUSY;
BUG_ON(!size);
BUG_ON(offset_in_page(size));
@@ -1139,6 +1140,10 @@ retry:
va->va_end = addr + size;
va->vm = NULL;
+ ret = kasan_populate_vmalloc(addr, size);
+ if (ret)
+ goto out;
+
spin_lock(&vmap_area_lock);
insert_vmap_area(va, &vmap_area_root, &vmap_area_list);
spin_unlock(&vmap_area_lock);
@@ -1169,8 +1174,9 @@ overflow:
pr_warn("vmap allocation for size %lu failed: use vmalloc=<size> to increase size\n",
size);
+out:
kmem_cache_free(vmap_area_cachep, va);
- return ERR_PTR(-EBUSY);
+ return ERR_PTR(ret);
}
int register_vmap_purge_notifier(struct notifier_block *nb)
@@ -1771,6 +1777,8 @@ void vm_unmap_ram(const void *mem, unsig
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 +1829,9 @@ void *vm_map_ram(struct page **pages, un
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 +2086,7 @@ static struct vm_struct *__get_vm_area_n
{
struct vmap_area *va;
struct vm_struct *area;
+ unsigned long requested_size = size;
BUG_ON(in_interrupt());
size = PAGE_ALIGN(size);
@@ -2098,23 +2110,9 @@ static struct vm_struct *__get_vm_area_n
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 +2291,7 @@ static void __vunmap(const void *addr, i
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 +2536,7 @@ void *__vmalloc_node_range(unsigned long
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 +2545,6 @@ void *__vmalloc_node_range(unsigned long
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 +3429,8 @@ 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);
_
Patches currently in -mm which might be from aryabinin@xxxxxxxxxxxxx are
kasan-fix-crashes-on-access-to-memory-mapped-by-vm_map_ram.patch
kasan-dont-allocate-page-tables-in-kasan_release_vmalloc.patch
