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@xxxxxxxxxxxx>
---
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
