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

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.

https://git.kernel.org/stable/c/1357fb32d42ad8da193e6da285f09e6452feabda

https://git.kernel.org/stable/c/18d4f86816592586b38513543b5e1f9553bc271f

https://git.kernel.org/stable/c/255fb7b0cdc947b1c01929c7f133281342a3a6b5

https://git.kernel.org/stable/c/4567ce79fe2f84c3dcc3a91b22a377cf482d33ad

https://git.kernel.org/stable/c/66aefc277ebb796ec285d550305535dc3fc0179f

https://git.kernel.org/stable/c/6c01f0439098f00a64b246dc27479602201382f7

https://git.kernel.org/stable/c/fbc1bdede66d0f2cde83b75d6524ce1a815bb69f

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