fpregs_state_valid in arch/x86/include/asm/fpu/internal.h in the Linux
kernel before 5.4.2, when GCC 9 is used, allows context-dependent attackers
to cause a denial of service (memory corruption) or possibly have
unspecified other impact because of incorrect fpu_fpregs_owner_ctx caching,
as demonstrated by mishandling of signal-based non-cooperative preemption
in Go 1.14 prereleases on amd64, aka CID-59c4bd853abc.

It was discovered that a race condition existed in the Linux kernel on x86
platforms when keeping track of which process was assigned control of the
FPU. A local attacker could use this to cause a denial of service (memory
corruption) or possibly gain administrative privileges.