ksmbd: fix Out-of-Bounds Write in ksmbd_vfs_stream_write

commit 313dab082289e460391c82d855430ec8a28ddf81 upstream.

An offset from client could be a negative value, It could allows
to write data outside the bounds of the allocated buffer.
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index ce6dff5c7d741c466752400099ffe43da949a11d..d0836d710f1814b002088fee6fd7047edcab2bcb 100644 (file)
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -6868,6 +6868,8 @@ int smb2_write(struct ksmbd_work *work)
        }
 
        offset = le64_to_cpu(req->Offset);
+       if (offset < 0)
+               return -EINVAL;
        length = le32_to_cpu(req->Length);
 
        if (req->Channel == SMB2_CHANNEL_RDMA_V1 ||