[149/212] kasan: test: avoid corrupting memory in kasan_rcu_uaf

Commit Message

Andrew Morton Sept. 2, 2021, 9:57 p.m. UTC

From: Andrey Konovalov <[e-mail]>
Subject: kasan: test: avoid corrupting memory in kasan_rcu_uaf

kasan_rcu_uaf() writes to freed memory via kasan_rcu_reclaim(), which is
only safe with the GENERIC mode (as it uses quarantine).  For other modes,
this test corrupts kernel memory, which might result in a crash.

Turn the write into a read.

Link: https://lkml.kernel.org/r/b6[e-mail]
Signed-off-by: Andrey Konovalov <[e-mail]>
Reviewed-by: Marco Elver <[e-mail]>
Cc: Alexander Potapenko <[e-mail]>
Cc: Andrey Ryabinin <[e-mail]>
Cc: Dmitry Vyukov <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 lib/test_kasan_module.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

--- a/lib/test_kasan_module.c~kasan-test-avoid-corrupting-memory-in-kasan_rcu_uaf
+++ a/lib/test_kasan_module.c
@@ -71,7 +71,7 @@  static noinline void __init kasan_rcu_re
 						struct kasan_rcu_info, rcu);
 
 	kfree(fp);
-	fp->i = 1;
+	((volatile struct kasan_rcu_info *)fp)->i;
 }
 
 static noinline void __init kasan_rcu_uaf(void)