ksmbd: fix Out-of-Bounds Write in ksmbd_vfs_stream_write

[ Upstream commit 313dab082289e460391c82d855430ec8a28ddf81 ]

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: Sasha Levin <sashal@kernel.org>

diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 35914c9809aa9d3be57c6e1b2c7411c270cccb21..0f97830d1ebcbb19f274fc35311e36b4ffe54bc5 100644 (file)
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -6567,6 +6567,8 @@ 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 ||