From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Currently, only kasan_report() checks the KASAN_BIT_REPORTED and
KASAN_BIT_MULTI_SHOT flags.
Make other reporting routines check these flags as well.
Also add explanatory comments.
Note that the current->kasan_depth check is split out into
report_suppressed() and only called for kasan_report().
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
---
mm/kasan/report.c | 35 ++++++++++++++++++++++++++++++++---
1 file changed, 32 insertions(+), 3 deletions(-)
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 08631d873204..ef649f5cee29 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -381,12 +381,26 @@ static void print_memory_metadata(const void *addr)
}
}
-static bool report_enabled(void)
+/*
+ * Used to suppress reports within kasan_disable/enable_current() critical
+ * sections, which are used for marking accesses to slab metadata.
+ */
+static bool report_suppressed(void)
{
#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
if (current->kasan_depth)
- return false;
+ return true;
#endif
+ return false;
+}
+
+/*
+ * Used to avoid reporting more than one KASAN bug unless kasan_multi_shot
+ * is enabled. Note that KASAN tests effectively enable kasan_multi_shot
+ * for their duration.
+ */
+static bool report_enabled(void)
+{
if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
return true;
return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags);
@@ -416,6 +430,14 @@ void kasan_report_invalid_free(void *ptr, unsigned long ip)
unsigned long flags;
struct kasan_report_info info;
+ /*
+ * Do not check report_suppressed(), as an invalid-free cannot be
+ * caused by accessing slab metadata and thus should not be
+ * suppressed by kasan_disable/enable_current() critical sections.
+ */
+ if (unlikely(!report_enabled()))
+ return;
+
start_report(&flags, true);
info.type = KASAN_REPORT_INVALID_FREE;
@@ -444,7 +466,7 @@ bool kasan_report(unsigned long addr, size_t size, bool is_write,
unsigned long irq_flags;
struct kasan_report_info info;
- if (unlikely(!report_enabled())) {
+ if (unlikely(report_suppressed()) || unlikely(!report_enabled())) {
ret = false;
goto out;
}
@@ -473,6 +495,13 @@ void kasan_report_async(void)
{
unsigned long flags;
+ /*
+ * Do not check report_suppressed(), as kasan_disable/enable_current()
+ * critical sections do not affect Hardware Tag-Based KASAN.
+ */
+ if (unlikely(!report_enabled()))
+ return;
+
start_report(&flags, false);
pr_err("BUG: KASAN: invalid-access\n");
pr_err("Asynchronous fault: no details available\n");
--
2.25.1
