[PATCH] fscrypt: Fix uninit-value in ovl_fill_real

[Qing Wang <wangqing7171@gmail.com>]

Syzbot reported a KMSAN uninit-value issue in ovl_fill_real and it was
allocated from fscrypt_fname_alloc_buffer. Fixed it by kzalloc.

The call chain is:
__do_sys_getdents64()
    -> iterate_dir()
        ...
            -> ext4_readdir()
                -> fscrypt_fname_alloc_buffer() // alloc
                -> dir_emit()
                    -> ovl_fill_real() // use by strcmp()

Reported-by: syzbot+d130f98b2c265fae5297@syzkaller.appspotmail.com
Close: https://syzkaller.appspot.com/bug?extid=d130f98b2c265fae5297
Signed-off-by: Qing Wang <wangqing7171@gmail.com>
---
 fs/crypto/fname.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
index a9a4432d12ba..ba8282b96a2e 100644
--- a/fs/crypto/fname.c
+++ b/fs/crypto/fname.c
@@ -220,7 +220,7 @@ int fscrypt_fname_alloc_buffer(u32 max_encrypted_len,
 	u32 max_presented_len = max_t(u32, FSCRYPT_NOKEY_NAME_MAX_ENCODED,
 				      max_encrypted_len);
 
-	crypto_str->name = kmalloc(max_presented_len + 1, GFP_NOFS);
+	crypto_str->name = kzalloc(max_presented_len + 1, GFP_NOFS);
 	if (!crypto_str->name)
 		return -ENOMEM;
 	crypto_str->len = max_presented_len;
-- 
2.34.1