Disable the efficient 8-byte reading under KMSAN to avoid false positives.
Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
To: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
---
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 --git a/lib/string.c b/lib/string.c
index 6012c385fb314..fec929e70f1a5 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;
--
2.25.1.696.g5e7596f4ac-goog
