CVE-2026-22998

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

nvme-tcp: fix NULL pointer dereferences in nvmet_tcp_build_pdu_iovec

Commit efa56305908b (nvmet-tcp: Fix a kernel panic when host sends an invalid H2C PDU length) added ttag bounds checking and data_offset validation in nvmet_tcp_handle_h2c_data_pdu(), but it did not validate whether the commands data structures (cmd->req.sg and cmd->iov) have been properly initialized before processing H2C_DATA PDUs.

The nvmet_tcp_build_pdu_iovec() function dereferences these pointers without NULL checks. This can be triggered by sending H2C_DATA PDU immediately after the ICREQ/ICRESP handshake, before sending a CONNECT command or NVMe write command.

Attack vectors that trigger NULL pointer dereferences:

1. H2C_DATA PDU sent before CONNECT → both pointers NULL
2. H2C_DATA PDU for READ command → cmd->req.sg allocated, cmd->iov NULL
3. H2C_DATA PDU for uninitialized command slot → both pointers NULL

The fix validates both cmd->req.sg and cmd->iov before calling nvmet_tcp_build_pdu_iovec(). Both checks are required because:

• Uninitialized commands: both NULL
• READ commands: cmd->req.sg allocated, cmd->iov NULL
• WRITE commands: both allocated

Affected Software

References

• https://git.kernel.org/stable/c/32b63acd78f577b332d976aa06b56e70d054cbba
• https://git.kernel.org/stable/c/374b095e265fa27465f34780e0eb162ff1bef913
• https://git.kernel.org/stable/c/3def5243150716be86599c2a1767c29c68838b6d
• https://git.kernel.org/stable/c/76abc83a9d25593c2b7613c549413079c14a4686
• https://git.kernel.org/stable/c/7d75570002929d20e40110d6b03e46202c9d1bc7
• https://git.kernel.org/stable/c/baabe43a0edefac8cd7b981ff87f967f6034dafe
• https://git.kernel.org/stable/c/fdecd3b6aac10d5a18d0dc500fe57f8648b66cd4