x86/process: Check PF_KTHREAD and not current->mm for kernel threads

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commit 12f7764ac6 upstream.

switch_fpu_finish() checks current->mm as indicator for kernel threads.
That's wrong because kernel threads can temporarily use a mm of a user
process via kthread_use_mm().

Check the task flags for PF_KTHREAD instead.

Fixes: 0cecca9d03 ("x86/fpu: Eager switch PKRU state")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20210608144345.912645927@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Thomas Gleixner 2021-06-08 16:36:20 +02:00 • committed by Greg Kroah-Hartman

parent ddaaf38e19

commit 75a55bc2e5

1 changed files with 1 additions and 1 deletions

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arch/x86/include/asm/fpu/internal.h

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