Linus Torvalds 1423e2660c Fixes and improvements for FPU handling on x86: ... - Prevent sigaltstack out of bounds writes. The kernel unconditionally writes the FPU state to the alternate stack without checking whether the stack is large enough to accomodate it. Check the alternate stack size before doing so and in case it's too small force a SIGSEGV instead of silently corrupting user space data. - MINSIGSTKZ and SIGSTKSZ are constants in signal.h and have never been updated despite the fact that the FPU state which is stored on the signal stack has grown over time which causes trouble in the field when AVX512 is available on a CPU. The kernel does not expose the minimum requirements for the alternate stack size depending on the available and enabled CPU features. ARM already added an aux vector AT_MINSIGSTKSZ for the same reason. Add it to x86 as well - A major cleanup of the x86 FPU code. The recent discoveries of XSTATE related issues unearthed quite some inconsistencies, duplicated code and other issues. The fine granular overhaul addresses this, makes the code more robust and maintainable, which allows to integrate upcoming XSTATE related features in sane ways. -----BEGIN PGP SIGNATURE----- iQJHBAABCgAxFiEEQp8+kY+LLUocC4bMphj1TA10mKEFAmDlcpETHHRnbHhAbGlu dXRyb25peC5kZQAKCRCmGPVMDXSYoeP5D/4i+AgYYeiMLgGb+NS7iaKPfoWo6LIz y3qdTSA0DQaIYbYivWwRO/g0GYdDMXDWeZalFi7eGnVI8O3eOog+22Zrf/y0UINB KJHdYd4ApWHhs401022y5hexrWQvnV8w1yQCuj/zLm6eC+AVhdwt2AY+IBoRrdUj wqY97B/4rJNsBvvqTDn9EeDrJA2y0y0Suc7AhIp2BGMI+dpIdxys8RJDamXNWyDL gJf0YRgUoiIn3AHKb+fgv60AoxfC175NSg/5/y/scFNXqVlW0Up4YCb7pqG9o2Ga f3XvtWfbw1N5PmUYjFkALwEkzGUbM3v0RA3xLY2j2WlWm9fBPPy59dt+i/h/VKyA GrA7i7lcIqX8dfVH6XkrReZBkRDSB6t9SZTvV54jAz5fcIZO2Rg++UFUvI/R6GKK XCcxukYaArwo+IG62iqDszS3gfLGhcor/cviOeULRC5zMUIO4Jah+IhDnifmShtC M5s9QzrwIRD/XMewGRQmvkiN4kBfE7jFoBQr1J9leCXJKrM+2JQmMzVInuubTQIq SdlKOaAIn7xtekz+6XdFG9Gmhck0PCLMJMOLNvQkKWI3KqGLRZ+dAWKK0vsCizAx 0BA7ZeB9w9lFT+D8mQCX77JvW9+VNwyfwIOLIrJRHk3VqVpS5qvoiFTLGJJBdZx4 /TbbRZu7nXDN2w== =Mq1m -----END PGP SIGNATURE----- Merge tag 'x86-fpu-2021-07-07' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 fpu updates from Thomas Gleixner: "Fixes and improvements for FPU handling on x86: - Prevent sigaltstack out of bounds writes. The kernel unconditionally writes the FPU state to the alternate stack without checking whether the stack is large enough to accomodate it. Check the alternate stack size before doing so and in case it's too small force a SIGSEGV instead of silently corrupting user space data. - MINSIGSTKZ and SIGSTKSZ are constants in signal.h and have never been updated despite the fact that the FPU state which is stored on the signal stack has grown over time which causes trouble in the field when AVX512 is available on a CPU. The kernel does not expose the minimum requirements for the alternate stack size depending on the available and enabled CPU features. ARM already added an aux vector AT_MINSIGSTKSZ for the same reason. Add it to x86 as well. - A major cleanup of the x86 FPU code. The recent discoveries of XSTATE related issues unearthed quite some inconsistencies, duplicated code and other issues. The fine granular overhaul addresses this, makes the code more robust and maintainable, which allows to integrate upcoming XSTATE related features in sane ways" * tag 'x86-fpu-2021-07-07' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (74 commits) x86/fpu/xstate: Clear xstate header in copy_xstate_to_uabi_buf() again x86/fpu/signal: Let xrstor handle the features to init x86/fpu/signal: Handle #PF in the direct restore path x86/fpu: Return proper error codes from user access functions x86/fpu/signal: Split out the direct restore code x86/fpu/signal: Sanitize copy_user_to_fpregs_zeroing() x86/fpu/signal: Sanitize the xstate check on sigframe x86/fpu/signal: Remove the legacy alignment check x86/fpu/signal: Move initial checks into fpu__restore_sig() x86/fpu: Mark init_fpstate __ro_after_init x86/pkru: Remove xstate fiddling from write_pkru() x86/fpu: Don't store PKRU in xstate in fpu_reset_fpstate() x86/fpu: Remove PKRU handling from switch_fpu_finish() x86/fpu: Mask PKRU from kernel XRSTOR[S] operations x86/fpu: Hook up PKRU into ptrace() x86/fpu: Add PKRU storage outside of task XSAVE buffer x86/fpu: Dont restore PKRU in fpregs_restore_userspace() x86/fpu: Rename xfeatures_mask_user() to xfeatures_mask_uabi() x86/fpu: Move FXSAVE_LEAK quirk info __copy_kernel_to_fpregs() x86/fpu: Rename __fpregs_load_activate() to fpregs_restore_userregs() ...		2021-07-07 11:12:01 -07:00
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asm	Fixes and improvements for FPU handling on x86:	2021-07-07 11:12:01 -07:00