diff mbox series

[v5,26/44] kmsan: disable strscpy() optimization under KMSAN

Message ID 20220826150807.723137-27-glider@google.com (mailing list archive)
State New
Headers show
Series Add KernelMemorySanitizer infrastructure | expand

Commit Message

Alexander Potapenko Aug. 26, 2022, 3:07 p.m. UTC 
Disable the efficient 8-byte reading under KMSAN to avoid false positives.

Signed-off-by: Alexander Potapenko <glider@google.com>

---

Link: https://linux-review.googlesource.com/id/Iffd8336965e88fce915db2e6a9d6524422975f69
---
 lib/string.c | 8 ++++++++
 1 file changed, 8 insertions(+)
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Patch

diff --git a/lib/string.c b/lib/string.c
index 6f334420f6871..3371d26a0e390 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -197,6 +197,14 @@  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;