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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Chinwen Chang <chinwen.chang@mediatek.com>,
        Nicholas Tang <nicholas.tang@mediatek.com>,
        Yee Lee <yee.lee@mediatek.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: [PATCH 5.10 078/599] mm/kmemleak: reset tag when compare object pointer
Date:   Tue,  5 Apr 2022 09:26:12 +0200
Message-Id: <20220405070301.147117364@linuxfoundation.org>
In-Reply-To: <20220405070258.802373272@linuxfoundation.org>
References: <20220405070258.802373272@linuxfoundation.org>
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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
@@ -787,6 +787,8 @@ 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) {
@@ -795,6 +797,9 @@ 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));
 
@@ -806,8 +811,8 @@ 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);