[PATCH 5.17 0110/1126] mm/kmemleak: reset tag when compare object pointer

Greg Kroah-Hartman
2022-04-05T07:47:07Z

From: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>

commit bfc8089f00fa526dea983844c880fa8106c33ac4 upstream.

When we use HW-tag based kasan and enable vmalloc support, we hit the
following bug. It is due to comparison between tagged object and
non-tagged pointer.

We need to reset the kasan tag when we need to compare tagged object and
non-tagged pointer.

kmemleak: [name:kmemleak&]Scan area larger than object 0xffffffe77076f440
CPU: 4 PID: 1 Comm: init Tainted: G S W 5.15.25-android13-0-g5cacf919c2bc #1
Hardware name: MT6983(ENG) (DT)
Call trace:
add_scan_area+0xc4/0x244
kmemleak_scan_area+0x40/0x9c
layout_and_allocate+0x1e8/0x288
load_module+0x2c8/0xf00
__se_sys_finit_module+0x190/0x1d0
__arm64_sys_finit_module+0x20/0x30
invoke_syscall+0x60/0x170
el0_svc_common+0xc8/0x114
do_el0_svc+0x28/0xa0
el0_svc+0x60/0xf8
el0t_64_sync_handler+0x88/0xec
el0t_64_sync+0x1b4/0x1b8
kmemleak: [name:kmemleak&]Object 0xf5ffffe77076b000 (size 32768):
kmemleak: [name:kmemleak&] comm "init", pid 1, jiffies 4294894197
kmemleak: [name:kmemleak&] min_count = 0
kmemleak: [name:kmemleak&] count = 0
kmemleak: [name:kmemleak&] flags = 0x1
kmemleak: [name:kmemleak&] checksum = 0
kmemleak: [name:kmemleak&] backtrace:
module_alloc+0x9c/0x120
move_module+0x34/0x19c
layout_and_allocate+0x1c4/0x288
load_module+0x2c8/0xf00
__se_sys_finit_module+0x190/0x1d0
__arm64_sys_finit_module+0x20/0x30
invoke_syscall+0x60/0x170
el0_svc_common+0xc8/0x114
do_el0_svc+0x28/0xa0
el0_svc+0x60/0xf8
el0t_64_sync_handler+0x88/0xec
el0t_64_sync+0x1b4/0x1b8

Link: https://lkml.kernel.org/r/20220318034051.30687-1-Kuan-Ying.Lee@mediatek.com
Signed-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Chinwen Chang <chinwen.chang@mediatek.com>
Cc: Nicholas Tang <nicholas.tang@mediatek.com>
Cc: Yee Lee <yee.lee@mediatek.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
mm/kmemleak.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -796,6 +796,8 @@ static void add_scan_area(unsigned long
unsigned long flags;
struct kmemleak_object *object;
struct kmemleak_scan_area *area = NULL;
+ unsigned long untagged_ptr;
+ unsigned long untagged_objp;

object = find_and_get_object(ptr, 1);
if (!object) {
@@ -804,6 +806,9 @@ static void add_scan_area(unsigned long
return;
}

+ untagged_ptr = (unsigned long)kasan_reset_tag((void *)ptr);
+ untagged_objp = (unsigned long)kasan_reset_tag((void *)object->pointer);
+
if (scan_area_cache)
area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));

@@ -815,8 +820,8 @@ static void add_scan_area(unsigned long
goto out_unlock;
}
if (size == SIZE_MAX) {
- size = object->pointer + object->size - ptr;
- } else if (ptr + size > object->pointer + object->size) {
+ size = untagged_objp + object->size - untagged_ptr;
+ } else if (untagged_ptr + size > untagged_objp + object->size) {
kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
dump_object_info(object);
kmem_cache_free(scan_area_cache, area);