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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: 1da177e4c3 ("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>
pull/1354/merge
Duoming Zhou 2025-10-28 18:01:49 +08:00 committed by Martin K. Petersen
parent 971bb08704
commit ab58153ec6
1 changed files with 1 additions and 0 deletions
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1
drivers/scsi/imm.c
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@ -1260,6 +1260,7 @@ static void imm_detach(struct parport *pb)
imm_struct *dev; imm_struct *dev;
list_for_each_entry(dev, &imm_hosts, list) { list_for_each_entry(dev, &imm_hosts, list) {
if (dev->dev->port == pb) { if (dev->dev->port == pb) {
disable_delayed_work_sync(&dev->imm_tq);
list_del_init(&dev->list); list_del_init(&dev->list);
scsi_remove_host(dev->host); scsi_remove_host(dev->host);
scsi_host_put(dev->host); scsi_host_put(dev->host);