scsi: qla2xxx: Fix use after free on unload

Vulnerability Description

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]

References

• https://git.kernel.org/stable/c/12f04fc8580eafb0510f805749553eb6213f323e
• https://git.kernel.org/stable/c/ca36d9d53745d5ec8946ef85006d4da605ea7c54
• https://git.kernel.org/stable/c/b3e6f25176f248762a24d25ab8cf8c5e90874f80
• https://git.kernel.org/stable/c/15369e774f27ec790f207de87c0b541e3f90b22d
• https://git.kernel.org/stable/c/6abf16d3c915b2feb68c1c8b25fcb71b13f98478
• https://git.kernel.org/stable/c/07c903db0a2ff84b68efa1a74a4de353ea591eb0