CVE-2026-89973

In the Linux kernel, the following vulnerability has been resolved:

nvme-tcp: check the data direction of a C2HData PDU

nvme_tcp_handle_c2h_data() finds the request by command id and checks that it has a payload, but it does not check that the command asked for data to be read. A controller that answers a write command with C2HData therefore reaches nvme_tcp_recv_data(), where _copy_to_iter() hits WARN_ON_ONCE(i->data_source) and returns 0. The receive path turns that into -EFAULT and resets the controller.

No data is copied, so this is not memory corruption. What a controller gets is a kernel warning it can raise at will, which is fatal on a host booted with panic_on_warn.

The send path already knows the direction - it consults rq_data_dir() when it builds a command - and nvme_tcp_handle_r2t() checks the length and the offset of the request it names. The C2HData path does not check the direction at all.

Reject a C2HData PDU whose command is not a read. Rejecting it fails the command and resets the controller, as the neighbouring check in this function does; what goes away is the warning.

[ 6.885580] ————[ cut here ]———— [ 6.886457] WARNING: lib/iov_iter.c:193 at _copy_to_iter+0x289/0x1330, CPU#0: kworker/0:1H/71 [ 6.888137] CPU: 0 UID: 0 PID: 71 Comm: kworker/0:1H Not tainted 7.2.0-rc5-NVMETCP-gf5098b6bae76 #1 PREEMPT(lazy) [ 6.891165] Workqueue: nvme_tcp_wq nvme_tcp_io_work [ 6.891875] RIP: 0010:_copy_to_iter+0x289/0x1330 [ 6.903739] Call Trace: [ 6.904085] [ 6.909254] __skb_datagram_iter+0x433/0x820 [ 6.911026] skb_copy_datagram_iter+0x37/0x120 [ 6.911622] nvme_tcp_recv_skb+0xa07/0x4320 [ 6.913378] __tcp_read_sock+0x1ab/0x810 [ 6.915788] nvme_tcp_try_recv+0x152/0x1e0 [ 6.918222] nvme_tcp_io_work+0x1e4/0x6c0 [ 6.926906] [ 6.927226] —[ end trace 0000000000000000 ]— [ 6.927878] nvme nvme0: queue 1 failed to copy request 0x71 data [ 6.928709] nvme nvme0: receive failed: -14

Affected Software

References

• https://git.kernel.org/stable/c/0673a2affe45ca76b60de31a83c67b1e60f81bde
• https://git.kernel.org/stable/c/5b115d932f6e769ac80783fb18edd21b0aed256e
• https://git.kernel.org/stable/c/80d56202fbdff8906be6954b2776e5c14a4026f2
• https://git.kernel.org/stable/c/980d990f3c0560d7dfbfbf14699651fdf02f26ee
• https://git.kernel.org/stable/c/a0c389b8a495bda1eb719d2503853c924b7a8355
• https://git.kernel.org/stable/c/b4af7999a998787d5eb6facb5a333e04a4f1d2d9
• https://git.kernel.org/stable/c/df74950ba6008655d4a977d17df7faf4b6e52b74
• https://git.kernel.org/stable/c/f83af377c148f6ad94b41c0e8313f12adf45e1c1