From: Yang Yingliang <yangyingliang@huawei.com>
Date: Mon, 31 May 2021 08:25:05 +0000 (+0900)
Subject: cifsd: check return value of ksmbd_vfs_getcasexattr() correctly
X-Git-Tag: v5.15-rc1~11^2~5^2~16^2~1
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=fd6de099d7fabc2b86f51dc622453eb279f7cce9;p=users%2Fdwmw2%2Flinux.git

cifsd: check return value of ksmbd_vfs_getcasexattr() correctly

If ksmbd_vfs_getcasexattr() returns -ENOMEM, stream_buf is NULL,
it will cause null-ptr-deref when using it to copy memory. So we
need check the return value of ksmbd_vfs_getcasexattr() by comparing
with 0.

Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
---

diff --git a/fs/cifsd/vfs.c b/fs/cifsd/vfs.c
index 85872416bf9b5..56b1091473b97 100644
--- a/fs/cifsd/vfs.c
+++ b/fs/cifsd/vfs.c
@@ -274,7 +274,6 @@ static int ksmbd_vfs_stream_read(struct ksmbd_file *fp, char *buf, loff_t *pos,
 {
 	ssize_t v_len;
 	char *stream_buf = NULL;
-	int err;
 
 	ksmbd_debug(VFS, "read stream data pos : %llu, count : %zd\n",
 		    *pos, count);
@@ -283,11 +282,8 @@ static int ksmbd_vfs_stream_read(struct ksmbd_file *fp, char *buf, loff_t *pos,
 				       fp->stream.name,
 				       fp->stream.size,
 				       &stream_buf);
-	if (v_len == -ENOENT) {
-		ksmbd_err("not found stream in xattr : %zd\n", v_len);
-		err = -ENOENT;
-		return err;
-	}
+	if ((int)v_len <= 0)
+		return (int)v_len;
 
 	memcpy(buf, &stream_buf[*pos], count);
 	kvfree(stream_buf);
@@ -415,9 +411,9 @@ static int ksmbd_vfs_stream_write(struct ksmbd_file *fp, char *buf, loff_t *pos,
 				       fp->stream.name,
 				       fp->stream.size,
 				       &stream_buf);
-	if (v_len == -ENOENT) {
+	if ((int)v_len < 0) {
 		ksmbd_err("not found stream in xattr : %zd\n", v_len);
-		err = -ENOENT;
+		err = (int)v_len;
 		goto out;
 	}