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scsi: imm: Fix use-after-free bug caused by unfinished delayed work

The delayed work item 'imm_tq' is initialized in imm_attach() and
scheduled via imm_queuecommand() for processing SCSI commands. When the
IMM parallel port SCSI host adapter is detached through imm_detach(),
the imm_struct device instance is deallocated.

However, the delayed work might still be pending or executing
when imm_detach() is called, leading to use-after-free bugs
when the work function imm_interrupt() accesses the already
freed imm_struct memory.

The race condition can occur as follows:

CPU 0(detach thread) | CPU 1
| imm_queuecommand()
| imm_queuecommand_lck()
imm_detach() | schedule_delayed_work()
kfree(dev) //FREE | imm_interrupt()
| dev = container_of(...) //USE
dev-> //USE

Add disable_delayed_work_sync() in imm_detach() to guarantee proper
cancellation of the delayed work item before imm_struct is deallocated.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Link: https://patch.msgid.link/20251028100149.40721-1-duoming@zju.edu.cn
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

authored by

Duoming Zhou and committed by
Martin K. Petersen ab58153e 971bb087

+1
+1
drivers/scsi/imm.c
··· 1260 1260 imm_struct *dev; 1261 1261 list_for_each_entry(dev, &imm_hosts, list) { 1262 1262 if (dev->dev->port == pb) { 1263 + disable_delayed_work_sync(&dev->imm_tq); 1263 1264 list_del_init(&dev->list); 1264 1265 scsi_remove_host(dev->host); 1265 1266 scsi_host_put(dev->host);