mm/thp: fix strncpy warning

Using MAX_INPUT_BUF_SZ as the maximum length of the string makes fortify
complain as it thinks the string might be longer than the buffer, and if
it is, we will end up with a "string" that is missing a NUL terminator.
It's trivial to show that 'tok' points to a NUL-terminated string which is
less than MAX_INPUT_BUF_SZ in length, so we may as well just use strcpy()
and avoid the warning.

Link: https://lkml.kernel.org/r/20210615200242.1716568-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 503c8e1aecc6bda55a64d45cddaaffb2b2b230eb..d513b0cd1161d97acfb33b5f56d862936e2eb95e 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3101,7 +3101,7 @@ static ssize_t split_huge_pages_write(struct file *file, const char __user *buf,
 
                tok = strsep(&buf, ",");
                if (tok) {
-                       strncpy(file_path, tok, MAX_INPUT_BUF_SZ);
+                       strcpy(file_path, tok);
                } else {
                        ret = -EINVAL;
                        goto out;