Messages in this thread | | | Date | Sun, 06 Jun 2021 01:47:42 +0200 | From | Thomas Gleixner <> | Subject | [patch V2 00/14] x86/fpu: Mop up XSAVES and related damage |
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syszbot reported a warnon for XRSTOR raising #GP:
https://lore.kernel.org/r/0000000000004c453905c30f8334@google.com
with a syzcaller reproducer and a conclusive bisect result. It took a while to destill a simple C reproducer out of it which allowed to pin point the root cause: The recent addition of supervisor XSTATEs broke the signal restore path for the case where the signal handler wreckaged the XSTATE on stack because it does not sanitize the XSTATE header which causes a subsequent XRSTOR to fail and #GP.
The following series addresses the problem and fixes related issues which were found while inspecting the related changes.
V1 of this can be found here:
https://lore.kernel.org/r/20210602095543.149814064@linutronix.de
Changes vs. V1:
- Address review comments
- Fix the reported fallout (mostly PKRU and PTRACE). The test cases pass now.
- Address the broken init_fpstate fiddling which was found by deeper inspection of the PKRU/XSTATE related code.
Thanks,
tglx ---
P.S: I picked up Dave's PKRU series from
https://lore.kernel.org/r/20210603230803.31660AFE@viggo.jf.intel.com
and adopted it to this pile. The result is here:
https://tglx.de/~tglx/patches-fpu-pkru.tar
There are some fixes at the end which I did no fold back yet and the glibc PKRU test case with all that applied still fails with:
../sysdeps/unix/sysv/linux/tst-pkey.c:377: numeric comparison failure left: 1 (0x1); from: result->access_rights[i] right: 0 (0x0); from: 0 ../sysdeps/unix/sysv/linux/tst-pkey.c:382: numeric comparison failure left: 1 (0x1); from: result2->access_rights[i] right: 0 (0x0); from: 0 error: 2 test failures
Too tired to analyze that right now, but I wanted to share the work. --- arch/x86/include/asm/fpu/internal.h | 17 -- arch/x86/include/asm/fpu/xstate.h | 10 - arch/x86/include/asm/pgtable.h | 6 arch/x86/include/asm/pkeys.h | 11 - arch/x86/kernel/cpu/bugs.c | 3 arch/x86/kernel/cpu/common.c | 27 +--- arch/x86/kernel/fpu/core.c | 119 ++++++++++++------ arch/x86/kernel/fpu/regset.c | 45 ++---- arch/x86/kernel/fpu/signal.c | 30 +++- arch/x86/kernel/fpu/xstate.c | 100 +++++---------- arch/x86/kernel/process.c | 14 +- arch/x86/mm/fault.c | 2 arch/x86/mm/pkeys.c | 31 ++-- b/tools/testing/selftests/x86/corrupt_xstate_header.c | 114 +++++++++++++++++ include/linux/pkeys.h | 2 tools/testing/selftests/x86/Makefile | 3 16 files changed, 334 insertions(+), 200 deletions(-)
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