CVE-2026-43054

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

scsi: target: tcm_loop: Drain commands in target_reset handler

tcm_loop_target_reset() violates the SCSI EH contract: it returns SUCCESS

without draining any in-flight commands. The SCSI EH documentation

(scsi_eh.rst) requires that when a reset handler returns SUCCESS the driver

has made lower layers "forget about timed out scmds" and is ready for new

commands. Every other SCSI LLD (virtio_scsi, mpt3sas, ipr, scsi_debug,

mpi3mr) enforces this by draining or completing outstanding commands before

returning SUCCESS.

Because tcm_loop_target_reset() doesn't drain, the SCSI EH reuses in-flight

scsi_cmnd structures for recovery commands (e.g. TUR) while the target core

still has async completion work queued for the old se_cmd. The memset in

queuecommand zeroes se_lun and lun_ref_active, causing

transport_lun_remove_cmd() to skip its percpu_ref_put(). The leaked LUN

reference prevents transport_clear_lun_ref() from completing, hanging

configfs LUN unlink forever in D-state:

INFO: task rm:264 blocked for more than 122 seconds.

rm D 0 264 258 0x00004000

Call Trace:

__schedule+0x3d0/0x8e0

schedule+0x36/0xf0

transport_clear_lun_ref+0x78/0x90 [target_core_mod]

core_tpg_remove_lun+0x28/0xb0 [target_core_mod]

target_fabric_port_unlink+0x50/0x60 [target_core_mod]

configfs_unlink+0x156/0x1f0 [configfs]

vfs_unlink+0x109/0x290

do_unlinkat+0x1d5/0x2d0

Fix this by making tcm_loop_target_reset() actually drain commands:

1. Issue TMR_LUN_RESET via tcm_loop_issue_tmr() to drain all commands that

the target core knows about (those not yet CMD_T_COMPLETE).

2. Use blk_mq_tagset_busy_iter() to iterate all started requests and

flush_work() on each se_cmd — this drains any deferred completion work

for commands that already had CMD_T_COMPLETE set before the TMR (which

the TMR skips via __target_check_io_state()). This is the same pattern

used by mpi3mr, scsi_debug, and libsas to drain outstanding commands

during reset.