mirror of
https://github.com/hardkernel/linux.git
synced 2026-06-05 10:31:46 +09:00
7cc16be1ae
commit5499802b22upstream. The conversion from __copy_from_user() to __get_user() by commitd3ccc97815("powerpc/signal: Use __get_user() to copy sigset_t") introduced a regression in __get_user_sigset() for powerpc/32. The bug was subsequently moved into unsafe_get_user_sigset(). The bug is due to the copied 64 bit value being truncated to 32 bits while being assigned to dst->sig[0] The regression was reported by users of the Xorg packages distributed in Debian/powerpc -- "The symptoms are that the fb screen goes blank, with the backlight remaining on and no errors logged in /var/log; wdm (or startx) run with no effect (I tried logging in in the blind, with no effect). And they are hard to kill, requiring 'kill -KILL ...'" Fix the regression by copying each word of the sigset, not only the first one. __get_user_sigset() was tentatively optimised to copy 64 bits at once in order to minimise KUAP unlock/lock impact, but the unsafe variant doesn't suffer that, so it can just copy words. Fixes:887f3ceb51("powerpc/signal32: Convert do_setcontext[_tm]() to user access block") Cc: stable@vger.kernel.org # v5.13+ Reported-by: Finn Thain <fthain@linux-m68k.org> Reported-and-tested-by: Stan Johnson <userm57@yahoo.com> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/99ef38d61c0eb3f79c68942deb0c35995a93a777.1636966353.git.christophe.leroy@csgroup.eu Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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.