In the Linux kernel, the following vulnerability has been resolved:
nvme-tcp: fix host memory disclosure on R2T for a read command
nvme_tcp_handle_r2t() does not check the direction of the request the
R2T refers to. A malicious controller can send an R2T for a READ and
the host will answer it: nvme_tcp_setup_h2c_data_pdu() builds the
H2CData header and nvme_tcp_try_send_data() sends the request’s data
buffer. That buffer is the READ destination, so its contents go to the
controller.
The command then completes normally and nothing is logged.
Against a test controller that answers every READ with an R2T, a 4096
byte buffered read returned all 4096 bytes, split over two R2Ts. The
pages contained stale kernel data, including an array of struct page
pointers.
Reject an R2T for a request that is not a write.
