ksmbd: fix Out-of-Bounds Read in ksmbd_vfs_stream_read

[ Upstream commit fc342cf86e2dc4d2edb0fc2ff5e28b6c7845adb9 ]

An offset from client could be a negative value, It could lead
to an out-of-bounds read from the stream_buf.
Note that this issue is coming when setting
'vfs objects = streams_xattr parameter' in ksmbd.conf.

Cc: stable@vger.kernel.org # v5.15+
Reported-by: Jordy Zomer <jordyzomer@google.com>
Signed-off-by: Jordy Zomer <jordyzomer@google.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 54f7cf7a98b2b5001bed27488ae5b6960a86391c..35914c9809aa9d3be57c6e1b2c7411c270cccb21 100644 (file)
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -6350,6 +6350,10 @@ int smb2_read(struct ksmbd_work *work)
        }
 
        offset = le64_to_cpu(req->Offset);
+       if (offset < 0) {
+               err = -EINVAL;
+               goto out;
+       }
        length = le32_to_cpu(req->Length);
        mincount = le32_to_cpu(req->MinimumCount);