linux-kernel - [PATCH v2] kasan:print the original fault addr when access invalid shadow

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Message-ID: <20231009073748.159228-1-haibo.li@mediatek.com>
Date:   Mon, 9 Oct 2023 15:37:48 +0800
From:   Haibo Li <haibo.li@...iatek.com>
To:     <linux-kernel@...r.kernel.org>
CC:     Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Alexander Potapenko <glider@...gle.com>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        "Andrew Morton" <akpm@...ux-foundation.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        <kasan-dev@...glegroups.com>, <linux-mm@...ck.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>, <xiaoming.yu@...iatek.com>,
        Haibo Li <haibo.li@...iatek.com>
Subject: [PATCH v2] kasan:print the original fault addr when access invalid shadow

when the checked address is illegal,the corresponding shadow address
from kasan_mem_to_shadow may have no mapping in mmu table.
Access such shadow address causes kernel oops.
Here is a sample about oops on arm64(VA 39bit) 
with KASAN_SW_TAGS and KASAN_OUTLINE on:

[ffffffb80aaaaaaa] pgd=000000005d3ce003, p4d=000000005d3ce003,
    pud=000000005d3ce003, pmd=0000000000000000
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 3 PID: 100 Comm: sh Not tainted 6.6.0-rc1-dirty #43
Hardware name: linux,dummy-virt (DT)
pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __hwasan_load8_noabort+0x5c/0x90
lr : do_ib_ob+0xf4/0x110
ffffffb80aaaaaaa is the shadow address for efffff80aaaaaaaa.
The problem is reading invalid shadow in kasan_check_range.

The generic kasan also has similar oops.

It only reports the shadow address which causes oops but not
the original address.

Commit 2f004eea0fc8("x86/kasan: Print original address on #GP")
introduce to kasan_non_canonical_hook but limit it to KASAN_INLINE.

This patch extends it to KASAN_OUTLINE mode.

Signed-off-by: Haibo Li <haibo.li@...iatek.com>
---
v2:
- In view of the possible perf impact by checking shadow address,change 
   to use kasan_non_canonical_hook as it works after oops.
---
 include/linux/kasan.h | 6 +++---
 mm/kasan/report.c     | 4 +---
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 3df5499f7936..a707ee8b19ce 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -466,10 +466,10 @@ static inline void kasan_free_module_shadow(const struct vm_struct *vm) {}
 
 #endif /* (CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS) && !CONFIG_KASAN_VMALLOC */
 
-#ifdef CONFIG_KASAN_INLINE
+#ifdef CONFIG_KASAN
 void kasan_non_canonical_hook(unsigned long addr);
-#else /* CONFIG_KASAN_INLINE */
+#else /* CONFIG_KASAN */
 static inline void kasan_non_canonical_hook(unsigned long addr) { }
-#endif /* CONFIG_KASAN_INLINE */
+#endif /* CONFIG_KASAN */
 
 #endif /* LINUX_KASAN_H */
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index ca4b6ff080a6..3974e4549c3e 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -621,9 +621,8 @@ void kasan_report_async(void)
 }
 #endif /* CONFIG_KASAN_HW_TAGS */
 
-#ifdef CONFIG_KASAN_INLINE
 /*
- * With CONFIG_KASAN_INLINE, accesses to bogus pointers (outside the high
+ * With CONFIG_KASAN, accesses to bogus pointers (outside the high
  * canonical half of the address space) cause out-of-bounds shadow memory reads
  * before the actual access. For addresses in the low canonical half of the
  * address space, as well as most non-canonical addresses, that out-of-bounds
@@ -659,4 +658,3 @@ void kasan_non_canonical_hook(unsigned long addr)
 	pr_alert("KASAN: %s in range [0x%016lx-0x%016lx]\n", bug_type,
 		 orig_addr, orig_addr + KASAN_GRANULE_SIZE - 1);
 }
-#endif
-- 
2.18.0