mm: fix benign off-by-one bugs

We were wasting a byte due to an off-by-one bug.  s[c]nprintf() doesn't
write more than $2 bytes including the null byte, so trying to pass
'size-1' there is wasting one byte.

Link: https://lkml.kernel.org/r/9c38dd009c17b0219889c7089d9bdde5aaf28a8e.1765449750.git.alx@kernel.org
Signed-off-by: Alejandro Colomar <[email protected]>
Acked-by: Marco Elver <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Christopher Bazley <[email protected]>
Cc: Alexander Potapenko <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Jann Horn <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Rasmus Villemoes <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Maciej W. Rozycki <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: alejandro-colomar

mm/kfence/kfence_test.c

@@ -110,7 +110,7 @@ static bool report_matches(const struct expect_report *r)
 
 	/* Title */
 	cur = expect[0];
-	end = &expect[0][sizeof(expect[0]) - 1];
+	end = ARRAY_END(expect[0]);
 	switch (r->type) {
 	case KFENCE_ERROR_OOB:
 		cur += scnprintf(cur, end - cur, "BUG: KFENCE: out-of-bounds %s",
@@ -140,7 +140,7 @@ static bool report_matches(const struct expect_report *r)
 
 	/* Access information */
 	cur = expect[1];
-	end = &expect[1][sizeof(expect[1]) - 1];
+	end = ARRAY_END(expect[1]);
 
 	switch (r->type) {
 	case KFENCE_ERROR_OOB:

mm/kmsan/kmsan_test.c

@@ -105,7 +105,7 @@ static bool report_matches(const struct expect_report *r)
 
 	/* Title */
 	cur = expected_header;
-	end = &expected_header[sizeof(expected_header) - 1];
+	end = ARRAY_END(expected_header);
 
 	cur += scnprintf(cur, end - cur, "BUG: KMSAN: %s", r->error_type);