From: Shuai Yuan <[email protected]>
Calling start_report() again between start_report() and end_report()
will result in a race issue for the report_lock. In extreme cases this
problem arose in Kunit tests in the hardware tag-based Kasan mode.
For example, when an invalid memory release problem is found,
kasan_report_invalid_free() will print error log, but if an MTE exception
is raised during the output log, the kasan_report() is called, resulting
in a deadlock problem. The kasan_depth not protect it in hardware
tag-based Kasan mode.
Signed-off-by: Shuai Yuan <[email protected]>
Reviewed-by: Weizhao Ouyang <[email protected]>
Reviewed-by: Peng Ren <[email protected]>
---
mm/kasan/report.c | 26 +++++++++++++++++++++-----
1 file changed, 21 insertions(+), 5 deletions(-)
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 22598b20c7b7..82aa75259cf4 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -166,7 +166,7 @@ static inline void fail_non_kasan_kunit_test(void) { }
static DEFINE_SPINLOCK(report_lock);
-static void start_report(unsigned long *flags, bool sync)
+static bool start_report(unsigned long *flags, bool sync)
{
fail_non_kasan_kunit_test();
/* Respect the /proc/sys/kernel/traceoff_on_warning interface. */
@@ -175,8 +175,14 @@ static void start_report(unsigned long *flags, bool sync)
lockdep_off();
/* Make sure we don't end up in loop. */
kasan_disable_current();
- spin_lock_irqsave(&report_lock, *flags);
+ if (!spin_trylock_irqsave(&report_lock, *flags)) {
+ lockdep_on();
+ kasan_enable_current();
+ pr_err("%s ignore\n", __func__);
+ return false;
+ }
pr_err("==================================================================\n");
+ return true;
}
static void end_report(unsigned long *flags, void *addr)
@@ -468,7 +474,10 @@ void kasan_report_invalid_free(void *ptr, unsigned long ip, enum kasan_report_ty
if (unlikely(!report_enabled()))
return;
- start_report(&flags, true);
+ if (!start_report(&flags, true)) {
+ pr_err("%s: start report ignore\n", __func__);
+ return;
+ }
memset(&info, 0, sizeof(info));
info.type = type;
@@ -500,10 +509,14 @@ bool kasan_report(unsigned long addr, size_t size, bool is_write,
if (unlikely(report_suppressed()) || unlikely(!report_enabled())) {
ret = false;
+ pr_err("%s: start report ignore\n", __func__);
goto out;
}
- start_report(&irq_flags, true);
+ if (!start_report(&irq_flags, true)) {
+ ret = false;
+ goto out;
+ }
memset(&info, 0, sizeof(info));
info.type = KASAN_REPORT_ACCESS;
@@ -536,7 +549,10 @@ void kasan_report_async(void)
if (unlikely(!report_enabled()))
return;
- start_report(&flags, false);
+ if (!start_report(&flags, false)) {
+ pr_err("%s: start report ignore\n", __func__);
+ return;
+ }
pr_err("BUG: KASAN: invalid-access\n");
pr_err("Asynchronous fault: no details available\n");
pr_err("\n");
--
2.25.1