In the Linux kernel, the following vulnerability has been resolved:
iommu/vt-d: Avoid memory allocation in iommu_suspend()
The iommususpend() syscore suspend callback is invoked with IRQ disabled. Allocating memory with the GFPKERNEL flag may re-enable IRQs during the suspend callback, which can cause intermittent suspend/hibernation problems with the following kernel traces:
Calling iommususpend+0x0/0x1d0 ------------[ cut here ]------------ WARNING: CPU: 0 PID: 15 at kernel/time/timekeeping.c:868 ktimeget+0x9b/0xb0 ... CPU: 0 PID: 15 Comm: rcupreempt Tainted: G U E 6.3-intel #r1 RIP: 0010:ktimeget+0x9b/0xb0 ... Call Trace: <IRQ> tickschedtimer+0x22/0x90 ? _pfxtickschedtimer+0x10/0x10 _hrtimerrunqueues+0x111/0x2b0 hrtimerinterrupt+0xfa/0x230 _sysvecapictimerinterrupt+0x63/0x140 sysvecapictimerinterrupt+0x7b/0xa0 </IRQ> <TASK> asmsysvecapictimerinterrupt+0x1f/0x30 ... ------------[ cut here ]------------ Interrupts enabled after iommususpend+0x0/0x1d0 WARNING: CPU: 0 PID: 27420 at drivers/base/syscore.c:68 syscoresuspend+0x147/0x270 CPU: 0 PID: 27420 Comm: rtcwake Tainted: G U W E 6.3-intel #r1 RIP: 0010:syscoresuspend+0x147/0x270 ... Call Trace: <TASK> hibernationsnapshot+0x25b/0x670 hibernate+0xcd/0x390 statestore+0xcf/0xe0 kobjattrstore+0x13/0x30 sysfskfwrite+0x3f/0x50 kernfsfopwriteiter+0x128/0x200 vfswrite+0x1fd/0x3c0 ksyswrite+0x6f/0xf0 _x64syswrite+0x1d/0x30 dosyscall64+0x3b/0x90 entrySYSCALL64afterhwframe+0x72/0xdc
Given that only 4 words memory is needed, avoid the memory allocation in iommu_suspend().