From dffad91b06e0a1ee584f008565cbf2bb508a9777 Mon Sep 17 00:00:00 2001
From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Date: Fri, 29 Apr 2022 14:38:01 -0700
Subject: lib/string.c: simplify str[c]spn

Use strchr(), which makes them a lot shorter, and more obviously symmetric
in their treatment of accept/reject.  It also saves a little bit of .text;
bloat-o-meter for an arm build says

Function                                     old     new   delta
strcspn                                       92      76     -16
strspn                                       108      76     -32

While here, also remove a stray empty line before EXPORT_SYMBOL().

Link: https://lkml.kernel.org/r/20220328224119.3003834-2-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 lib/string.c | 25 ++++++-------------------
 1 file changed, 6 insertions(+), 19 deletions(-)

(limited to 'lib/string.c')

diff --git a/lib/string.c b/lib/string.c
index 485777c9da83..6f334420f687 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -517,21 +517,13 @@ EXPORT_SYMBOL(strnlen);
 size_t strspn(const char *s, const char *accept)
 {
 	const char *p;
-	const char *a;
-	size_t count = 0;
 
 	for (p = s; *p != '\0'; ++p) {
-		for (a = accept; *a != '\0'; ++a) {
-			if (*p == *a)
-				break;
-		}
-		if (*a == '\0')
-			return count;
-		++count;
+		if (!strchr(accept, *p))
+			break;
 	}
-	return count;
+	return p - s;
 }
-
 EXPORT_SYMBOL(strspn);
 #endif
 
@@ -544,17 +536,12 @@ EXPORT_SYMBOL(strspn);
 size_t strcspn(const char *s, const char *reject)
 {
 	const char *p;
-	const char *r;
-	size_t count = 0;
 
 	for (p = s; *p != '\0'; ++p) {
-		for (r = reject; *r != '\0'; ++r) {
-			if (*p == *r)
-				return count;
-		}
-		++count;
+		if (strchr(reject, *p))
+			break;
 	}
-	return count;
+	return p - s;
 }
 EXPORT_SYMBOL(strcspn);
 #endif
-- 
cgit 


From 2de6f3bf75058e35eff04e6fab7ca41533bdb027 Mon Sep 17 00:00:00 2001
From: Alexander Potapenko <glider@google.com>
Date: Thu, 15 Sep 2022 17:03:59 +0200
Subject: kmsan: disable strscpy() optimization under KMSAN

Disable the efficient 8-byte reading under KMSAN to avoid false positives.

Link: https://lkml.kernel.org/r/20220915150417.722975-26-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Marco Elver <elver@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 lib/string.c | 8 ++++++++
 1 file changed, 8 insertions(+)

(limited to 'lib/string.c')

diff --git a/lib/string.c b/lib/string.c
index 6f334420f687..3371d26a0e39 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;
 
-- 
cgit