Vasily Gorbik 2ed924f278 s390/vdso: correct vdso mapping for compat tasks
[ Upstream commit 190f056fba ]

While "s390/vdso: avoid 64-bit vdso mapping for compat tasks" fixed
64-bit vdso mapping for compat tasks under gdb it introduced another
problem. "compat_mm" flag is not inherited during fork and when
31-bit process forks a child (but does not perform exec) it ends up
with 64-bit vdso. To address that, init_new_context (which is called
during fork and exec) now initialize compat_mm based on thread TIF_31BIT
flag. Later compat_mm is adjusted in arch_setup_additional_pages, which
is called during exec.

Fixes: d1befa6582 ("s390/vdso: avoid 64-bit vdso mapping for compat tasks")
Reported-by: Stefan Liebler <stli@linux.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: <stable@vger.kernel.org> # v4.20+
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-11-20 18:47:53 +01:00
2019-11-12 19:21:46 +01:00

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.
See Documentation/00-INDEX for a list of what is contained in each file.

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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