CVE-2024-56623

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

scsi: qla2xxx: Fix use after free on unload

System crash is observed with stack trace warning of use after free. There are 2 signals to tell dpc_thread to terminate (UNLOADING flag and kthread_stop).

On setting the UNLOADING flag when dpc_thread happens to run at the time and sees the flag, this causes dpc_thread to exit and clean up itself. When kthread_stop is called for final cleanup, this causes use after free.

Remove UNLOADING signal to terminate dpc_thread. Use the kthread_stop as the main signal to exit dpc_thread.

[596663.812935] kernel BUG at mm/slub.c:294! [596663.812950] invalid opcode: 0000 [#1] SMP PTI [596663.812957] CPU: 13 PID: 1475935 Comm: rmmod Kdump: loaded Tainted: G IOE --------- - - 4.18.0-240.el8.x86_64 #1 [596663.812960] Hardware name: HP ProLiant DL380p Gen8, BIOS P70 08/20/2012 [596663.812974] RIP: 0010:__slab_free+0x17d/0x360

... [596663.813008] Call Trace: [596663.813022] ? __dentry_kill+0x121/0x170 [596663.813030] ? _cond_resched+0x15/0x30 [596663.813034] ? _cond_resched+0x15/0x30 [596663.813039] ? wait_for_completion+0x35/0x190 [596663.813048] ? try_to_wake_up+0x63/0x540 [596663.813055] free_task+0x5a/0x60 [596663.813061] kthread_stop+0xf3/0x100 [596663.813103] qla2x00_remove_one+0x284/0x440 [qla2xxx]

This vulnerability is rated Moderate because triggering the race condition requires local administrative privileges to initiate kernel module unloading, limiting the attack surface to privileged users. Systems are only exposed if they have QLogic Fibre Channel Host Bus Adapter hardware or virtualized devices attached that load the qla2xxx driver. In typical enterprise environments, kernel modules for storage controllers are loaded during boot and rarely unloaded during production operations, reducing the likelihood of accidental denial of service.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.