From: Alexander Sverdlin <[email protected]>
In case CONFIG_KASAN_VMALLOC=y kasan_populate_vmalloc() allocates the
shadow pages dynamically. But even worse is that kasan_release_vmalloc()
releases them, which is not compatible with create_mapping() of
MODULES_VADDR..MODULES_END range:
BUG: Bad page state in process kworker/9:1 pfn:2068b
page:e5e06160 refcount:0 mapcount:0 mapping:00000000 index:0x0
flags: 0x1000(reserved)
raw: 00001000 e5e06164 e5e06164 00000000 00000000 00000000 ffffffff 00000000
page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
bad because of flags: 0x1000(reserved)
Modules linked in: ip_tables
CPU: 9 PID: 154 Comm: kworker/9:1 Not tainted 5.4.188-... #1
Hardware name: LSI Axxia AXM55XX
Workqueue: events do_free_init
unwind_backtrace
show_stack
dump_stack
bad_page
free_pcp_prepare
free_unref_page
kasan_depopulate_vmalloc_pte
__apply_to_page_range
apply_to_existing_page_range
kasan_release_vmalloc
__purge_vmap_area_lazy
_vm_unmap_aliases.part.0
__vunmap
do_free_init
process_one_work
worker_thread
kthread
Reviewed-by: Linus Walleij <[email protected]>
Signed-off-by: Alexander Sverdlin <[email protected]>
---
Changelog:
v2:
* more verbose comment
arch/arm/mm/kasan_init.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/arch/arm/mm/kasan_init.c b/arch/arm/mm/kasan_init.c
index 29caee9..46d9f4a 100644
--- a/arch/arm/mm/kasan_init.c
+++ b/arch/arm/mm/kasan_init.c
@@ -268,12 +268,17 @@ void __init kasan_init(void)
/*
* 1. The module global variables are in MODULES_VADDR ~ MODULES_END,
- * so we need to map this area.
+ * so we need to map this area if CONFIG_KASAN_VMALLOC=n. With
+ * VMALLOC support KASAN will manage this region dynamically,
+ * refer to kasan_populate_vmalloc() and ARM's implementation of
+ * module_alloc().
* 2. PKMAP_BASE ~ PKMAP_BASE+PMD_SIZE's shadow and MODULES_VADDR
* ~ MODULES_END's shadow is in the same PMD_SIZE, so we can't
* use kasan_populate_zero_shadow.
*/
- create_mapping((void *)MODULES_VADDR, (void *)(PKMAP_BASE + PMD_SIZE));
+ if (!IS_ENABLED(CONFIG_KASAN_VMALLOC) && IS_ENABLED(CONFIG_MODULES))
+ create_mapping((void *)MODULES_VADDR, (void *)(MODULES_END));
+ create_mapping((void *)PKMAP_BASE, (void *)(PKMAP_BASE + PMD_SIZE));
/*
* KAsan may reuse the contents of kasan_early_shadow_pte directly, so
--
2.10.2
On Mon, Sep 5, 2022 at 2:28 PM Alexander A Sverdlin
<[email protected]> wrote:
> From: Alexander Sverdlin <[email protected]>
>
> In case CONFIG_KASAN_VMALLOC=y kasan_populate_vmalloc() allocates the
> shadow pages dynamically. But even worse is that kasan_release_vmalloc()
> releases them, which is not compatible with create_mapping() of
> MODULES_VADDR..MODULES_END range:
>
> BUG: Bad page state in process kworker/9:1 pfn:2068b
> page:e5e06160 refcount:0 mapcount:0 mapping:00000000 index:0x0
> flags: 0x1000(reserved)
> raw: 00001000 e5e06164 e5e06164 00000000 00000000 00000000 ffffffff 00000000
> page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
> bad because of flags: 0x1000(reserved)
> Modules linked in: ip_tables
> CPU: 9 PID: 154 Comm: kworker/9:1 Not tainted 5.4.188-... #1
> Hardware name: LSI Axxia AXM55XX
> Workqueue: events do_free_init
> unwind_backtrace
> show_stack
> dump_stack
> bad_page
> free_pcp_prepare
> free_unref_page
> kasan_depopulate_vmalloc_pte
> __apply_to_page_range
> apply_to_existing_page_range
> kasan_release_vmalloc
> __purge_vmap_area_lazy
> _vm_unmap_aliases.part.0
> __vunmap
> do_free_init
> process_one_work
> worker_thread
> kthread
>
> Reviewed-by: Linus Walleij <[email protected]>
> Signed-off-by: Alexander Sverdlin <[email protected]>
Thanks Alexander, will you submit this to Russell's patch tracker please?
Yours,
Linus Walleij
Hello Linus,
On 05/09/2022 15:38, Linus Walleij wrote:
>> In case CONFIG_KASAN_VMALLOC=y kasan_populate_vmalloc() allocates the
>> shadow pages dynamically. But even worse is that kasan_release_vmalloc()
>> releases them, which is not compatible with create_mapping() of
>> MODULES_VADDR..MODULES_END range:
>>
>> BUG: Bad page state in process kworker/9:1 pfn:2068b
[...]
>>
>> Reviewed-by: Linus Walleij <[email protected]>
>> Signed-off-by: Alexander Sverdlin <[email protected]>
> Thanks Alexander, will you submit this to Russell's patch tracker please?
done!
https://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=9242/1
Thank you for the quick review!
--
Best regards,
Alexander Sverdlin.