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Date:   Fri, 14 Aug 2020 19:27:14 +0200
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Subject: [PATCH 32/35] kasan, arm64: print report from tag fault handler
From:   Andrey Konovalov <andreyknvl@google.com>
To:     Dmitry Vyukov <dvyukov@google.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        kasan-dev@googlegroups.com
Cc:     Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        Marco Elver <elver@google.com>,
        Evgenii Stepanov <eugenis@google.com>,
        Elena Petrova <lenaptr@google.com>,
        Branislav Rankov <Branislav.Rankov@arm.com>,
        Kevin Brodsky <kevin.brodsky@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        Andrey Konovalov <andreyknvl@google.com>
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Add error reporting for hardware tag-based KASAN. When CONFIG_KASAN_HW_TAGS
is enabled, print KASAN report from the arm64 tag fault handler.

SAS bits aren't set in ESR for all faults reported in EL1, so it's
impossible to find out the size of the access the caused the fault.
Adapt KASAN reporting code to handle this case.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 arch/arm64/mm/fault.c |  9 +++++++++
 mm/kasan/report.c     | 11 ++++++++---
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index c62c8ba85c0e..cf00b3942564 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -14,6 +14,7 @@
 #include <linux/mm.h>
 #include <linux/hardirq.h>
 #include <linux/init.h>
+#include <linux/kasan.h>
 #include <linux/kprobes.h>
 #include <linux/uaccess.h>
 #include <linux/page-flags.h>
@@ -314,11 +315,19 @@ static void report_tag_fault(unsigned long addr, unsigned int esr,
 {
 	bool is_write = ((esr & ESR_ELx_WNR) >> ESR_ELx_WNR_SHIFT) != 0;
 
+#ifdef CONFIG_KASAN_HW_TAGS
+	/*
+	 * SAS bits aren't set for all faults reported in EL1, so we can't
+	 * find out access size.
+	 */
+	kasan_report(addr, 0, is_write, regs->pc);
+#else
 	pr_alert("Memory Tagging Extension Fault in %pS\n", (void *)regs->pc);
 	pr_alert("  %s at address %lx\n", is_write ? "Write" : "Read", addr);
 	pr_alert("  Pointer tag: [%02x], memory tag: [%02x]\n",
 			mte_get_ptr_tag(addr),
 			mte_get_mem_tag((void *)addr));
+#endif
 }
 
 static void __do_kernel_fault(unsigned long addr, unsigned int esr,
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index c904edab33b8..34ef81736d73 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -65,9 +65,14 @@ static void print_error_description(struct kasan_access_info *info)
 {
 	pr_err("BUG: KASAN: %s in %pS\n",
 		get_bug_type(info), (void *)info->ip);
-	pr_err("%s of size %zu at addr %px by task %s/%d\n",
-		info->is_write ? "Write" : "Read", info->access_size,
-		info->access_addr, current->comm, task_pid_nr(current));
+	if (info->access_size)
+		pr_err("%s of size %zu at addr %px by task %s/%d\n",
+			info->is_write ? "Write" : "Read", info->access_size,
+			info->access_addr, current->comm, task_pid_nr(current));
+	else
+		pr_err("%s at addr %px by task %s/%d\n",
+			info->is_write ? "Write" : "Read",
+			info->access_addr, current->comm, task_pid_nr(current));
 }
 
 static DEFINE_SPINLOCK(report_lock);
-- 
2.28.0.220.ged08abb693-goog