diff mbox series

[RFC,v4,36/42] kmsan: disable strscpy() optimization under KMSAN

Message ID 20191220184955.223741-37-glider@google.com (mailing list archive)
State New, archived
Headers show
Series Add KernelMemorySanitizer infrastructure | expand

Commit Message

Alexander Potapenko Dec. 20, 2019, 6:49 p.m. UTC 
Disable the efficient 8-byte reading under KMSAN to avoid false positives.

Signed-off-by: Alexander Potapenko <glider@google.com>
To: Alexander Potapenko <glider@google.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: linux-mm@kvack.org

---

v4:
 - actually disable the optimization under KMSAN via max=0
 - use IS_ENABLED as requested by Marco Elver

Change-Id: I25d1acf5c3df6eff85894cd94f5ddbe93308271c
---
 lib/string.c | 8 ++++++++
 1 file changed, 8 insertions(+)
diff mbox series

Patch

diff --git a/lib/string.c b/lib/string.c
index 08ec58cc673b..8f7fb0617240 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -202,6 +202,14 @@  ssize_t strscpy(char *dest, const char *src, size_t count)
 		max = 0;
 #endif
 
+	/*
+	 * read_word_at_a_time() below may read uninitialized bytes after the
+	 * trailing zero and use them in comparisons. Disable this optimization
+	 * under KMSAN to prevent false positive reports.
+	 */
+	if (IS_ENABLED(CONFIG_KMSAN))
+		max = 0;
+
 	while (max >= sizeof(unsigned long)) {
 		unsigned long c, data;