[PATCH] mm/kmemleak: Reset tag when compare object pointer
From: Kuan-Ying Lee
Date: Thu Mar 17 2022 - 23:41:18 EST
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.
[ 7.690429][T400001] init: kmemleak: [name:kmemleak&]Scan area larger than object 0xffffffe77076f440
[ 7.691762][T400001] init: CPU: 4 PID: 1 Comm: init Tainted: G S W 5.15.25-android13-0-g5cacf919c2bc #1
[ 7.693218][T400001] init: Hardware name: MT6983(ENG) (DT)
[ 7.693983][T400001] init: Call trace:
[ 7.694508][T400001] init: dump_backtrace.cfi_jt+0x0/0x8
[ 7.695272][T400001] init: dump_stack_lvl+0xac/0x120
[ 7.695985][T400001] init: add_scan_area+0xc4/0x244
[ 7.696685][T400001] init: kmemleak_scan_area+0x40/0x9c
[ 7.697428][T400001] init: layout_and_allocate+0x1e8/0x288
[ 7.698211][T400001] init: load_module+0x2c8/0xf00
[ 7.698895][T400001] init: __se_sys_finit_module+0x190/0x1d0
[ 7.699701][T400001] init: __arm64_sys_finit_module+0x20/0x30
[ 7.700517][T400001] init: invoke_syscall+0x60/0x170
[ 7.701225][T400001] init: el0_svc_common+0xc8/0x114
[ 7.701933][T400001] init: do_el0_svc+0x28/0xa0
[ 7.702580][T400001] init: el0_svc+0x60/0xf8
[ 7.703196][T400001] init: el0t_64_sync_handler+0x88/0xec
[ 7.703964][T400001] init: el0t_64_sync+0x1b4/0x1b8
[ 7.704658][T400001] init: kmemleak: [name:kmemleak&]Object 0xf5ffffe77076b000 (size 32768):
[ 7.705824][T400001] init: kmemleak: [name:kmemleak&] comm "init", pid 1, jiffies 4294894197
[ 7.707002][T400001] init: kmemleak: [name:kmemleak&] min_count = 0
[ 7.707886][T400001] init: kmemleak: [name:kmemleak&] count = 0
[ 7.708718][T400001] init: kmemleak: [name:kmemleak&] flags = 0x1
[ 7.709574][T400001] init: kmemleak: [name:kmemleak&] checksum = 0
[ 7.710440][T400001] init: kmemleak: [name:kmemleak&] backtrace:
[ 7.711284][T400001] init: module_alloc+0x9c/0x120
[ 7.712015][T400001] init: move_module+0x34/0x19c
[ 7.712735][T400001] init: layout_and_allocate+0x1c4/0x288
[ 7.713561][T400001] init: load_module+0x2c8/0xf00
[ 7.714291][T400001] init: __se_sys_finit_module+0x190/0x1d0
[ 7.715142][T400001] init: __arm64_sys_finit_module+0x20/0x30
[ 7.716004][T400001] init: invoke_syscall+0x60/0x170
[ 7.716758][T400001] init: el0_svc_common+0xc8/0x114
[ 7.717512][T400001] init: do_el0_svc+0x28/0xa0
[ 7.718207][T400001] init: el0_svc+0x60/0xf8
[ 7.718869][T400001] init: el0t_64_sync_handler+0x88/0xec
[ 7.719683][T400001] init: el0t_64_sync+0x1b4/0x1b8
Signed-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@xxxxxxxxxxxx>
---
mm/kmemleak.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 7580baa76af1..acd7cbb82e16 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -796,6 +796,8 @@ static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
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 ptr, size_t size, gfp_t gfp)
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 ptr, size_t size, gfp_t gfp)
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);
--
2.18.0