Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [tip: x86/fpu] x86/fpu/xstate: Define new functions for clearing fpregs and xstates | Date | Tue, 25 May 2021 20:00:12 +0200 |
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On Tue, May 25 2021 at 10:44, Yu-cheng Yu wrote: > On 5/24/2021 9:34 AM, Andy Lutomirski wrote: >> So I'm guessing that syzbot may have misattributed the problem. But >> we definitely need to clean up the XRSTOR #GP handling before CET >> lands. >> > From the crash dump, the system is doing syscall_exit_to_user_mode() > for __x64_sys_futex(). The futex syscall does not seem to modify > xstates,
Of course does the futex syscall not modify anything, but the task can schedule out before returning from the syscall so it has to restore the FPU state.
> but upon returning to user mode, XRSTORS gets a GP. Can this > be some memory corruption? fpu__clear() is merely helping to clear the > mess and seems to be innocent.
What kind of analysis is that?
Thanks,
tglx
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