5ef2d5231d
If the guarded storage regset for current is supposed to be changed,
the regset from user space is copied directly into the guarded storage
control block.
If then the process gets scheduled away while the control block is
being copied and before the new control block has been loaded, the
result is random: the process can be scheduled away due to a page
fault or preemption. If that happens the already copied parts will be
overwritten by save_gs_cb(), called from switch_to().
Avoid this by copying the data to a temporary buffer on the stack and
do the actual update with preemption disabled.
Fixes: f5bbd7219891 ("s390/ptrace: guarded storage regset for the current task")
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. 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.