Andy Lutomirski 95443fc0d7 x86/entry/32: Fix FIXUP_ESPFIX_STACK with user CR3
commit 4a13b0e3e1 upstream.

UNWIND_ESPFIX_STACK needs to read the GDT, and the GDT mapping that
can be accessed via %fs is not mapped in the user pagetables.  Use
SGDT to find the cpu_entry_area mapping and read the espfix offset
from that instead.

Reported-and-tested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-11-29 10:10:00 +01:00
2019-11-29 10:09:47 +01:00
2019-11-24 16:32:01 -08:00

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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