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Subject[PATCH v8 11/20] kasan, arm64: fix up fault handling logic
Date
show_pte in arm64 fault handling relies on the fact that the top byte of
a kernel pointer is 0xff, which isn't always the case with tag-based
KASAN.

This patch resets the top byte in show_pte.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
arch/arm64/mm/fault.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 50b30ff30de4..78328c864d01 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -32,6 +32,7 @@
#include <linux/perf_event.h>
#include <linux/preempt.h>
#include <linux/hugetlb.h>
+#include <linux/kasan.h>

#include <asm/bug.h>
#include <asm/cmpxchg.h>
@@ -134,6 +135,8 @@ void show_pte(unsigned long addr)
pgd_t *pgdp;
pgd_t pgd;

+ addr = (unsigned long)kasan_reset_tag((void *)addr);
+
if (addr < TASK_SIZE) {
/* TTBR0 */
mm = current->active_mm;
--
2.19.0.397.gdd90340f6a-goog
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