Linux kernel libiscsi: out-of-bounds read leaks stale connection data into the SCSI sense buffer

Impact

iscsi_scsi_cmd_rsp() checks the received data segment length against the sense length without accounting for the 2-byte sense-length prefix, so a target that returns datalen == senselen makes the copy read up to two bytes past the received data. Those bytes are stale conn->data contents from earlier traffic on the same iSCSI connection, and they are handed to userspace in the command's sense buffer. The leak is small and bounded — two bytes of adjacent connection buffer per response — but it crosses from kernel connection state into whatever process issued the SCSI command. Only nodes that mount storage over the iSCSI initiator are affected; a GPU node with no iSCSI-backed volumes never reaches this code.

Who can reach it

Requires control over the responses of an iSCSI target the node's initiator is connected to — a malicious or compromised target, or an attacker able to inject responses into an unauthenticated iSCSI session on the storage network. No credentials on the GPU node itself are needed.

What to do

The fix is merged upstream and backported across stable branches (five stable commits are listed on the record). Update the host kernel from your distribution and reboot each initiator node; there is no runtime mitigation short of not using the iSCSI initiator. The record does not name distribution package versions, only the stable commits.

References