diff options
| author | Peilin Ye <yepeilin.cs@gmail.com> | 2020-09-24 09:43:48 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-10-14 10:32:56 +0200 |
| commit | 1b2fcd82c0ca23f6fa01298c0d7b59eb4efbaf48 (patch) | |
| tree | 06f4870b919b9200c167775776413aaa9f39e517 /drivers/video | |
| parent | f51ec3fd71284531205981858b192970ec46770e (diff) | |
fbcon: Fix global-out-of-bounds read in fbcon_get_font()
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>
Diffstat (limited to 'drivers/video')
| -rw-r--r-- | drivers/video/fbdev/core/fbcon.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c index dc7f5c4f0607..4cf71ee0965a 100644 --- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -2292,6 +2292,9 @@ static int fbcon_get_font(struct vc_data *vc, struct console_font *font) if (font->width <= 8) { j = vc->vc_font.height; + if (font->charcount * j > FNTSIZE(fontdata)) + return -EINVAL; + for (i = 0; i < font->charcount; i++) { memcpy(data, fontdata, j); memset(data + j, 0, 32 - j); @@ -2300,6 +2303,9 @@ static int fbcon_get_font(struct vc_data *vc, struct console_font *font) } } else if (font->width <= 16) { j = vc->vc_font.height * 2; + if (font->charcount * j > FNTSIZE(fontdata)) + return -EINVAL; + for (i = 0; i < font->charcount; i++) { memcpy(data, fontdata, j); memset(data + j, 0, 64 - j); @@ -2307,6 +2313,9 @@ static int fbcon_get_font(struct vc_data *vc, struct console_font *font) fontdata += j; } } else if (font->width <= 24) { + if (font->charcount * (vc->vc_font.height * sizeof(u32)) > FNTSIZE(fontdata)) + return -EINVAL; + for (i = 0; i < font->charcount; i++) { for (j = 0; j < vc->vc_font.height; j++) { *data++ = fontdata[0]; @@ -2319,6 +2328,9 @@ static int fbcon_get_font(struct vc_data *vc, struct console_font *font) } } else { j = vc->vc_font.height * 4; + if (font->charcount * j > FNTSIZE(fontdata)) + return -EINVAL; + for (i = 0; i < font->charcount; i++) { memcpy(data, fontdata, j); memset(data + j, 0, 128 - j); |