From 66aefc277ebb796ec285d550305535dc3fc0179f Mon Sep 17 00:00:00 2001 From: Michael Bommarito Date: Thu, 11 Jun 2026 08:30:46 -0400 Subject: [PATCH] scsi: xen: scsiback: Free the command tag on the TMR submit-failure path scsiback_device_action() obtains a command tag in scsiback_get_pend_req() and submits a task-management request with target_submit_tmr(). When target_submit_tmr() fails it returns < 0 and scsiback jumps to the err: label, which sends a response but frees nothing, leaking the tag. Impact: a pvSCSI guest can leak the command tags of a LUN's session, stopping the LUN, by issuing VSCSIIF_ACT_SCSI_ABORT or RESET requests whenever target_submit_tmr() fails. transport_generic_free_cmd() cannot be used here. By the time target_submit_tmr() returns an error it has already run __target_init_cmd() (so se_cmd->cmd_kref is one, not zero), and on its target_get_sess_cmd() error path it has freed se_cmd->se_tmr_req via core_tmr_release_req() while leaving SCF_SCSI_TMR_CDB set and the pointer dangling. Letting the command release run target_free_cmd_mem() would then double-free se_tmr_req. Use the same helper, which returns just the tag, on this path too. Fixes: 2dbcdf33dbf6 ("xen-scsiback: Convert to percpu_ida tag allocation") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Michael Bommarito Reviewed-by: Juergen Gross Link: https://patch.msgid.link/20260611123046.2323342-3-michael.bommarito@gmail.com Signed-off-by: Martin K. Petersen --- drivers/xen/xen-scsiback.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c index f324732eba7f..c7036e0e41bd 100644 --- a/drivers/xen/xen-scsiback.c +++ b/drivers/xen/xen-scsiback.c @@ -658,7 +658,7 @@ static void scsiback_device_action(struct vscsibk_pend *pending_req, return; err: - scsiback_do_resp_with_sense(NULL, err, 0, pending_req); + scsiback_resp_and_free(pending_req, err); } /*