commit 5af08640795b2b9a940c9266c0260455377ae262 upstream.
fbcon_get_font() is reading out-of-bounds. A malicious user may resize
`vc->vc_font.height` to a large value, causing fbcon_get_font() to
read out of `fontdata`.
fbcon_get_font() handles both built-in and user-provided fonts.
Fortunately, recently we have added FONT_EXTRA_WORDS support for built-in
fonts, so fix it by adding range checks using FNTSIZE().
This patch depends on patch "fbdev, newport_con: Move FONT_EXTRA_WORDS
macros into linux/font.h", and patch "Fonts: Support FONT_EXTRA_WORDS
macros for built-in fonts".
Cc: stable@vger.kernel.org
Reported-and-tested-by: syzbot+29d4ed7f3bdedf2aa2fd@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=08b8be45afea11888776f897895aef9ad1c3ecfd
Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/b34544687a1a09d6de630659eb7a773f4953238b.1600953813.git.yepeilin.cs@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ 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>
commit 06a0df4d1b8b13b551668e47b11fd7629033b7df upstream.
Since the softscroll code got removed, this argument is always zero and
makes no sense any more.
Tested-by: Yuan Ming <yuanmingbuaa@gmail.com>
Tested-by: Willy Tarreau <w@1wt.eu>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 50145474f6ef4a9c19205b173da6264a644c7489 upstream.
This (and the VGA soft scrollback) turns out to have various nasty small
special cases that nobody really is willing to fight. The soft
scrollback code was really useful a few decades ago when you typically
used the console interactively as the main way to interact with the
machine, but that just isn't the case any more.
So it's not worth dragging along.
Tested-by: Yuan Ming <yuanmingbuaa@gmail.com>
Tested-by: Willy Tarreau <w@1wt.eu>
Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 39b3cffb8cf3111738ea993e2757ab382253d86a upstream.
Add a check to fbcon_resize() to ensure that a possible change to user font
height or user font width will not allow a font data out-of-bounds access.
NOTE: must use original charcount in calculation as font charcount can
change and cannot be used to determine the font data allocated size.
Signed-off-by: George Kennedy <george.kennedy@oracle.com>
Cc: stable <stable@vger.kernel.org>
Reported-by: syzbot+38a3699c7eaf165b97a6@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/1596213192-6635-1-git-send-email-george.kennedy@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Du Cheng