FKIE_CVE-2026-43054

Vulnerability from fkie_nvd - Published: 2026-05-01 15:16 - Updated: 2026-05-01 15:24
Severity ?
Summary
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.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/05ac3754467363558a0a54ae4bb7c89b2c9574cf
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/103f79e4949513247d763c6e7f3cbbf62017afdf
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/1333eee56cdf3f0cf67c6ab4114c2c9e0a952026
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/15f5241d5a52364a7e7867b49128b0442dbcad9d
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/757c43c692294cdfad31390accc0e90429b2ef8a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/7cbd69aaa507b1245240a28022bf5da0f07c68d9
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a836054ea81014117ec6b73529a21626a9e1f829
Impacted products
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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nscsi: target: tcm_loop: Drain commands in target_reset handler\n\ntcm_loop_target_reset() violates the SCSI EH contract: it returns SUCCESS\nwithout draining any in-flight commands.  The SCSI EH documentation\n(scsi_eh.rst) requires that when a reset handler returns SUCCESS the driver\nhas made lower layers \"forget about timed out scmds\" and is ready for new\ncommands.  Every other SCSI LLD (virtio_scsi, mpt3sas, ipr, scsi_debug,\nmpi3mr) enforces this by draining or completing outstanding commands before\nreturning SUCCESS.\n\nBecause tcm_loop_target_reset() doesn\u0027t drain, the SCSI EH reuses in-flight\nscsi_cmnd structures for recovery commands (e.g. TUR) while the target core\nstill has async completion work queued for the old se_cmd.  The memset in\nqueuecommand zeroes se_lun and lun_ref_active, causing\ntransport_lun_remove_cmd() to skip its percpu_ref_put().  The leaked LUN\nreference prevents transport_clear_lun_ref() from completing, hanging\nconfigfs LUN unlink forever in D-state:\n\n  INFO: task rm:264 blocked for more than 122 seconds.\n  rm              D    0   264    258 0x00004000\n  Call Trace:\n   __schedule+0x3d0/0x8e0\n   schedule+0x36/0xf0\n   transport_clear_lun_ref+0x78/0x90 [target_core_mod]\n   core_tpg_remove_lun+0x28/0xb0 [target_core_mod]\n   target_fabric_port_unlink+0x50/0x60 [target_core_mod]\n   configfs_unlink+0x156/0x1f0 [configfs]\n   vfs_unlink+0x109/0x290\n   do_unlinkat+0x1d5/0x2d0\n\nFix this by making tcm_loop_target_reset() actually drain commands:\n\n 1. Issue TMR_LUN_RESET via tcm_loop_issue_tmr() to drain all commands that\n    the target core knows about (those not yet CMD_T_COMPLETE).\n\n 2. Use blk_mq_tagset_busy_iter() to iterate all started requests and\n    flush_work() on each se_cmd \u2014 this drains any deferred completion work\n    for commands that already had CMD_T_COMPLETE set before the TMR (which\n    the TMR skips via __target_check_io_state()).  This is the same pattern\n    used by mpi3mr, scsi_debug, and libsas to drain outstanding commands\n    during reset."
    }
  ],
  "id": "CVE-2026-43054",
  "lastModified": "2026-05-01T15:24:14.893",
  "metrics": {},
  "published": "2026-05-01T15:16:51.910",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/05ac3754467363558a0a54ae4bb7c89b2c9574cf"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/103f79e4949513247d763c6e7f3cbbf62017afdf"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/1333eee56cdf3f0cf67c6ab4114c2c9e0a952026"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/15f5241d5a52364a7e7867b49128b0442dbcad9d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/757c43c692294cdfad31390accc0e90429b2ef8a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7cbd69aaa507b1245240a28022bf5da0f07c68d9"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a836054ea81014117ec6b73529a21626a9e1f829"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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