Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
scsi: core: pair EH runtime PM get and put
shost->eh_noresume is currently consulted twice in one error handling iteration: once before scsi_autopm_get_host() and once again before scsi_autopm_put_host().
That is racy when a PM-triggered error path flips shost->eh_noresume while the SCSI EH thread is still running.
The problem flow looks like this: PM path ufshcd_set_dev_pwr_mode() shost->eh_noresume = 1 ufshcd_execute_start_stop <– trigger EH … shost->eh_noresume = 0
EH path scsi_error_handler() if (!shost->eh_noresume) scsi_autopm_get_host() <– skipped … if (!shost->eh_noresume) scsi_autopm_put_host() <– executed later
In that case one EH iteration can skip autoresume on entry and still drop a runtime PM reference on exit. That leaves an unmatched runtime PM put and can trigger a runtime PM usage count underflow.
Fix this by making eh_noresume a regular bool so it can be accessed with READ_ONCE() and WRITE_ONCE(). Snapshot it once per EH iteration and use that snapshot for both runtime PM get and put decisions.
Details
- Affected product:
- AlmaLinux 9.2 ESU , CentOS 7 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , Debian 10 ELS , Debian 11 ELS , RHEL 7 ELS , TuxCare 9.6 ESU , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS , Ubuntu 20.04 ELS
- Affected packages:
- kernel @ 5.14.0 (+11 more)