kfence: add test suite

Add KFENCE test suite, testing various error detection scenarios. Makes
use of KUnit for test organization. Since KFENCE's interface to obtain
error reports is via the console, the test verifies that KFENCE outputs
expected reports to the console.

[elver@google.com: fix typo in test]
  Link: https://lkml.kernel.org/r/X9lHQExmHGvETxY4@elver.google.com
[elver@google.com: show access type in report]
  Link: https://lkml.kernel.org/r/20210111091544.3287013-2-elver@google.com

Link: https://lkml.kernel.org/r/20201103175841.3495947-9-elver@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Marco Elver <elver@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Co-developed-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Jann Horn <jannh@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hillf Danton <hdanton@sina.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joern Engel <joern@purestorage.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: SeongJae Park <sjpark@amazon.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 18 insertions, 9 deletions

diff --git a/mm/kfence/report.c b/mm/kfence/report.c
index 4dbfa9a382e4..901bd7ee83d8 100644
--- a/mm/kfence/report.c
+++ b/mm/kfence/report.c
@@ -156,7 +156,12 @@ static void print_diff_canary(unsigned long address, size_t bytes_to_show,
 	pr_cont(" ]");
 }
 
-void kfence_report_error(unsigned long address, struct pt_regs *regs,
+static const char *get_access_type(bool is_write)
+{
+	return is_write ? "write" : "read";
+}
+
+void kfence_report_error(unsigned long address, bool is_write, struct pt_regs *regs,
 			 const struct kfence_metadata *meta, enum kfence_error_type type)
 {
 	unsigned long stack_entries[KFENCE_STACK_DEPTH] = { 0 };
@@ -194,17 +199,19 @@ void kfence_report_error(unsigned long address, struct pt_regs *regs,
 	case KFENCE_ERROR_OOB: {
 		const bool left_of_object = address < meta->addr;
 
-		pr_err("BUG: KFENCE: out-of-bounds in %pS\n\n", (void *)stack_entries[skipnr]);
-		pr_err("Out-of-bounds access at 0x" PTR_FMT " (%luB %s of kfence-#%zd):\n",
-		       (void *)address,
+		pr_err("BUG: KFENCE: out-of-bounds %s in %pS\n\n", get_access_type(is_write),
+		       (void *)stack_entries[skipnr]);
+		pr_err("Out-of-bounds %s at 0x" PTR_FMT " (%luB %s of kfence-#%zd):\n",
+		       get_access_type(is_write), (void *)address,
 		       left_of_object ? meta->addr - address : address - meta->addr,
 		       left_of_object ? "left" : "right", object_index);
 		break;
 	}
 	case KFENCE_ERROR_UAF:
-		pr_err("BUG: KFENCE: use-after-free in %pS\n\n", (void *)stack_entries[skipnr]);
-		pr_err("Use-after-free access at 0x" PTR_FMT " (in kfence-#%zd):\n",
-		       (void *)address, object_index);
+		pr_err("BUG: KFENCE: use-after-free %s in %pS\n\n", get_access_type(is_write),
+		       (void *)stack_entries[skipnr]);
+		pr_err("Use-after-free %s at 0x" PTR_FMT " (in kfence-#%zd):\n",
+		       get_access_type(is_write), (void *)address, object_index);
 		break;
 	case KFENCE_ERROR_CORRUPTION:
 		pr_err("BUG: KFENCE: memory corruption in %pS\n\n", (void *)stack_entries[skipnr]);
@@ -213,8 +220,10 @@ void kfence_report_error(unsigned long address, struct pt_regs *regs,
 		pr_cont(" (in kfence-#%zd):\n", object_index);
 		break;
 	case KFENCE_ERROR_INVALID:
-		pr_err("BUG: KFENCE: invalid access in %pS\n\n", (void *)stack_entries[skipnr]);
-		pr_err("Invalid access at 0x" PTR_FMT ":\n", (void *)address);
+		pr_err("BUG: KFENCE: invalid %s in %pS\n\n", get_access_type(is_write),
+		       (void *)stack_entries[skipnr]);
+		pr_err("Invalid %s at 0x" PTR_FMT ":\n", get_access_type(is_write),
+		       (void *)address);
 		break;
 	case KFENCE_ERROR_INVALID_FREE:
 		pr_err("BUG: KFENCE: invalid free in %pS\n\n", (void *)stack_entries[skipnr]);