From 795b760fe741c0b82508947e7b76803a2cdabd13 Mon Sep 17 00:00:00 2001
From: Andrey Konovalov <andreyknvl@google.com>
Date: Thu, 24 Mar 2022 18:13:03 -0700
Subject: [PATCH] kasan: add comment about UACCESS regions to kasan_report

Add a comment explaining why kasan_report() is the only reporting function
that uses user_access_save/restore().

Link: https://lkml.kernel.org/r/1201ca3c2be42c7bd077c53d2e46f4a51dd1476a.1646237226.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/kasan/report.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 7915af810815..08631d873204 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -430,6 +430,11 @@ void kasan_report_invalid_free(void *ptr, unsigned long ip)
 	end_report(&flags, ptr);
 }
 
+/*
+ * kasan_report() is the only reporting function that uses
+ * user_access_save/restore(): kasan_report_invalid_free() cannot be called
+ * from a UACCESS region, and kasan_report_async() is not used on x86.
+ */
 bool kasan_report(unsigned long addr, size_t size, bool is_write,
 			unsigned long ip)
 {