[PATCH 1/2] afs: replace deprecated strcpy with strscpy in afs_lookup_atsys

[Thorsten Blum]

strcpy() has been deprecated [1] because it performs no bounds checking
on the destination buffer, which can lead to buffer overflows. Replace
it with the safer strscpy(), drop the manual length check and the
now-unused local length variable.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strcpy [1]
Signed-off-by: Thorsten Blum <thorsten.blum at linux.dev>
---
 fs/afs/dir.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/fs/afs/dir.c b/fs/afs/dir.c
index 78caef3f1338..89d5c9c354d4 100644
--- a/fs/afs/dir.c
+++ b/fs/afs/dir.c
@@ -9,6 +9,7 @@
 #include <linux/fs.h>
 #include <linux/namei.h>
 #include <linux/pagemap.h>
+#include <linux/string.h>
 #include <linux/swap.h>
 #include <linux/ctype.h>
 #include <linux/sched.h>
@@ -914,7 +915,7 @@ static struct dentry *afs_lookup_atsys(struct inode *dir, struct dentry *dentry)
 	struct afs_net *net = afs_i2net(dir);
 	struct dentry *ret;
 	char *buf, *p, *name;
-	int len, i;
+	int i;
 
 	_enter("");
 
@@ -935,13 +936,11 @@ static struct dentry *afs_lookup_atsys(struct inode *dir, struct dentry *dentry)
 
 	for (i = 0; i < subs->nr; i++) {
 		name = subs->subs[i];
-		len = dentry->d_name.len - 4 + strlen(name);
-		if (len >= AFSNAMEMAX) {
+		if (strscpy(p, name, AFSNAMEMAX - (p - buf)) < 0) {
 			ret = ERR_PTR(-ENAMETOOLONG);
 			goto out_s;
 		}
 
-		strcpy(p, name);
 		ret = lookup_noperm(&QSTR(buf), dentry->d_parent);
 		if (IS_ERR(ret) || d_is_positive(ret))
 			goto out_s;