Thomas Gleixner 7dbcf2b0b7 x86/irq/64: Limit IST stack overflow check to #DB stack
Commit

  37fe6a42b3 ("x86: Check stack overflow in detail")

added a broad check for the full exception stack area, i.e. it considers
the full exception stack area as valid.

That's wrong in two aspects:

 1) It does not check the individual areas one by one

 2) #DF, NMI and #MCE are not enabling interrupts which means that a
    regular device interrupt cannot happen in their context. In fact if a
    device interrupt hits one of those IST stacks that's a bug because some
    code path enabled interrupts while handling the exception.

Limit the check to the #DB stack and consider all other IST stacks as
'overflow' or invalid.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>
Cc: Nicolai Stange <nstange@suse.de>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190414160143.682135110@linutronix.de
2019-04-17 12:06:56 +02:00
2019-03-07 18:32:03 -08:00
2019-04-17 11:46:27 +02:00
2019-04-02 18:12:44 -10:00
2019-04-14 15:17:41 -07:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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