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authorAndrey Ryabinin <aryabinin@virtuozzo.com>2019-12-17 20:51:38 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-12-17 20:59:59 -0800
commitd98c9e83b5e7ca78175df1b13ac4a6d460d3962d (patch)
treed978ad6db67a7bc39ac92ef36e8b22b06a4e13eb /mm
parent2187f215ebaac73ddbd814696d7c7fa34f0c3de0 (diff)
downloadlinux-d98c9e83b5e7ca78175df1b13ac4a6d460d3962d.tar.bz2
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: 3c5c3cfb9ef4 ("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>
Diffstat (limited to 'mm')
-rw-r--r--mm/kasan/common.c27
-rw-r--r--mm/vmalloc.c85
2 files changed, 58 insertions, 54 deletions
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 2fa710bb6358..e04e73603dfc 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -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)
{
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 4d3b3d60d893..6e865cea846c 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1062,6 +1062,26 @@ __alloc_vmap_area(unsigned long size, unsigned long align,
}
/*
+ * 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:
@@ -1186,26 +1214,6 @@ 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
*/
static void unmap_vmap_area(struct vmap_area *va)
@@ -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);