[PATCH AUTOSEL 6.0 45/46] ARM: 9242/1: kasan: Only map modules if CONFIG_KASAN_VMALLOC=n

Sasha Levin
2022-10-11T14:55:09Z

From: Alex Sverdlin <alexander.sverdlin@nokia.com>

[ Upstream commit 823f606ab6b4759a1faf0388abcf4fb0776710d2 ]

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 <linus.walleij@linaro.org>
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 29caee9c79ce..46d9f4a622cb 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
--
2.35.1