73d58890be
[ Upstream commit ec0972adecb391a8d8650832263a4790f3bfb4df ]
syzbot is reporting OOB read at fbcon_resize() [1], for
commit 39b3cffb8cf31117 ("fbcon: prevent user font height or width change
from causing potential out-of-bounds access") is by error using
registered_fb[con2fb_map[vc->vc_num]]->fbcon_par->p->userfont (which was
set to non-zero) instead of fb_display[vc->vc_num].userfont (which remains
zero for that display).
We could remove tricky userfont flag [2], for we can determine it by
comparing address of the font data and addresses of built-in font data.
But since that commit is failing to fix the original OOB read [3], this
patch keeps the change minimal in case we decide to revert altogether.
[1] https://syzkaller.appspot.com/bug?id=ebcbbb6576958a496500fee9cf7aa83ea00b5920
[2] https://syzkaller.appspot.com/text?tag=Patch&x=14030853900000
[3] https://syzkaller.appspot.com/bug?id=6fba8c186d97cf1011ab17660e633b1cc4e080c9
Reported-by: syzbot <syzbot+b38b1ef6edf0c74a8d97@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Fixes: 39b3cffb8cf31117 ("fbcon: prevent user font height or width change from causing potential out-of-bounds access")
Cc: George Kennedy <george.kennedy@oracle.com>
Link: https://lore.kernel.org/r/f6e3e611-8704-1263-d163-f52c906a4f06@I-love.SAKURA.ne.jp
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.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.