Fonts: Support FONT_EXTRA_WORDS macros for built-in fonts

syzbot has reported an issue in the framebuffer layer, where a malicious
user may overflow our built-in font data buffers.

In order to perform a reliable range check, subsystems need to know
`FONTDATAMAX` for each built-in font. Unfortunately, our font descriptor,
`struct console_font` does not contain `FONTDATAMAX`, and is part of the
UAPI, making it infeasible to modify it.

For user-provided fonts, the framebuffer layer resolves this issue by
reserving four extra words at the beginning of data buffers. Later,
whenever a function needs to access them, it simply uses the following
macros:

Recently we have gathered all the above macros to <linux/font.h>. Let us
do the same thing for built-in fonts, prepend four extra words (including
`FONTDATAMAX`) to their data buffers, so that subsystems can use these
macros for all fonts, no matter built-in or user-provided.

This patch depends on patch "fbdev, newport_con: Move FONT_EXTRA_WORDS
macros into linux/font.h".

Cc: stable@vger.kernel.org
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/ef18af00c35fb3cc826048a5f70924ed6ddce95b.1600953813.git.yepeilin.cs@gmail.com

diff --git a/include/linux/font.h b/include/linux/font.h
index 40ed008..59faa80 100644 (file)
--- a/include/linux/font.h
+++ b/include/linux/font.h
@@ -67,4 +67,9 @@ extern const struct font_desc *get_default_font(int xres, int yres,
 
 #define FONT_EXTRA_WORDS 4
 
+struct font_data {
+       unsigned int extra[FONT_EXTRA_WORDS];
+       const unsigned char data[];
+} __packed;
+
 #endif /* _VIDEO_FONT_H */

diff --git a/lib/fonts/font_10x18.c b/lib/fonts/font_10x18.c
index 532f0ff..0e2deac 100644 (file)
--- a/lib/fonts/font_10x18.c
+++ b/lib/fonts/font_10x18.c
@@ -8,8 +8,8 @@
 
 #define FONTDATAMAX 9216
 
-static const unsigned char fontdata_10x18[FONTDATAMAX] = {
-
+static struct font_data fontdata_10x18 = {
+       { 0, 0, FONTDATAMAX, 0 }, {
        /* 0 0x00 '^@' */
        0x00, 0x00, /* 0000000000 */
        0x00, 0x00, /* 0000000000 */
@@ -5129,8 +5129,7 @@ static const unsigned char fontdata_10x18[FONTDATAMAX] = {
        0x00, 0x00, /* 0000000000 */
        0x00, 0x00, /* 0000000000 */
        0x00, 0x00, /* 0000000000 */
-
-};
+} };
 
 
 const struct font_desc font_10x18 = {
@@ -5138,7 +5137,7 @@ const struct font_desc font_10x18 = {
        .name   = "10x18",
        .width  = 10,
        .height = 18,
-       .data   = fontdata_10x18,
+       .data   = fontdata_10x18.data,
 #ifdef __sparc__
        .pref   = 5,
 #else

diff --git a/lib/fonts/font_6x10.c b/lib/fonts/font_6x10.c
index 09b2cc0..87da8ac 100644 (file)
--- a/lib/fonts/font_6x10.c
+++ b/lib/fonts/font_6x10.c
@@ -1,8 +1,10 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/font.h>
 
-static const unsigned char fontdata_6x10[] = {
+#define FONTDATAMAX 2560
 
+static struct font_data fontdata_6x10 = {
+       { 0, 0, FONTDATAMAX, 0 }, {
        /* 0 0x00 '^@' */
        0x00, /* 00000000 */
        0x00, /* 00000000 */
@@ -3074,14 +3076,13 @@ static const unsigned char fontdata_6x10[] = {
        0x00, /* 00000000 */
        0x00, /* 00000000 */
        0x00, /* 00000000 */
-
-};
+} };
 
 const struct font_desc font_6x10 = {
        .idx    = FONT6x10_IDX,
        .name   = "6x10",
        .width  = 6,
        .height = 10,
-       .data   = fontdata_6x10,
+       .data   = fontdata_6x10.data,
        .pref   = 0,
 };

diff --git a/lib/fonts/font_6x11.c b/lib/fonts/font_6x11.c
index d7136c3..5e975df 100644 (file)
--- a/lib/fonts/font_6x11.c
+++ b/lib/fonts/font_6x11.c
@@ -9,8 +9,8 @@
 
 #define FONTDATAMAX (11*256)
 
-static const unsigned char fontdata_6x11[FONTDATAMAX] = {
-
+static struct font_data fontdata_6x11 = {
+       { 0, 0, FONTDATAMAX, 0 }, {
        /* 0 0x00 '^@' */
        0x00, /* 00000000 */
        0x00, /* 00000000 */
@@ -3338,8 +3338,7 @@ static const unsigned char fontdata_6x11[FONTDATAMAX] = {
        0x00, /* 00000000 */
        0x00, /* 00000000 */
        0x00, /* 00000000 */
-
-};
+} };
 
 
 const struct font_desc font_vga_6x11 = {
@@ -3347,7 +3346,7 @@ const struct font_desc font_vga_6x11 = {
        .name   = "ProFont6x11",
        .width  = 6,
        .height = 11,
-       .data   = fontdata_6x11,
+       .data   = fontdata_6x11.data,
        /* Try avoiding this font if possible unless on MAC */
        .pref   = -2000,
 };

diff --git a/lib/fonts/font_7x14.c b/lib/fonts/font_7x14.c
index 89752d0..86d298f 100644 (file)
--- a/lib/fonts/font_7x14.c
+++ b/lib/fonts/font_7x14.c
@@ -8,8 +8,8 @@
 
 #define FONTDATAMAX 3584
 
-static const unsigned char fontdata_7x14[FONTDATAMAX] = {
-
+static struct font_data fontdata_7x14 = {
+       { 0, 0, FONTDATAMAX, 0 }, {
        /* 0 0x00 '^@' */
        0x00, /* 0000000 */
        0x00, /* 0000000 */
@@ -4105,8 +4105,7 @@ static const unsigned char fontdata_7x14[FONTDATAMAX] = {
        0x00, /* 0000000 */
        0x00, /* 0000000 */
        0x00, /* 0000000 */
-
-};
+} };
 
 
 const struct font_desc font_7x14 = {
@@ -4114,6 +4113,6 @@ const struct font_desc font_7x14 = {
        .name   = "7x14",
        .width  = 7,
        .height = 14,
-       .data   = fontdata_7x14,
+       .data   = fontdata_7x14.data,
        .pref   = 0,
 };

diff --git a/lib/fonts/font_8x16.c b/lib/fonts/font_8x16.c
index b7ab1f5..37cedd3 100644 (file)
--- a/lib/fonts/font_8x16.c
+++ b/lib/fonts/font_8x16.c
@@ -10,8 +10,8 @@
 
 #define FONTDATAMAX 4096
 
-static const unsigned char fontdata_8x16[FONTDATAMAX] = {
-
+static struct font_data fontdata_8x16 = {
+       { 0, 0, FONTDATAMAX, 0 }, {
        /* 0 0x00 '^@' */
        0x00, /* 00000000 */
        0x00, /* 00000000 */
@@ -4619,8 +4619,7 @@ static const unsigned char fontdata_8x16[FONTDATAMAX] = {
        0x00, /* 00000000 */
        0x00, /* 00000000 */
        0x00, /* 00000000 */
-
-};
+} };
 
 
 const struct font_desc font_vga_8x16 = {
@@ -4628,7 +4627,7 @@ const struct font_desc font_vga_8x16 = {
        .name   = "VGA8x16",
        .width  = 8,
        .height = 16,
-       .data   = fontdata_8x16,
+       .data   = fontdata_8x16.data,
        .pref   = 0,
 };
 EXPORT_SYMBOL(font_vga_8x16);

diff --git a/lib/fonts/font_8x8.c b/lib/fonts/font_8x8.c
index 2328ebc..8ab6955 100644 (file)
--- a/lib/fonts/font_8x8.c
+++ b/lib/fonts/font_8x8.c
@@ -9,8 +9,8 @@
 
 #define FONTDATAMAX 2048
 
-static const unsigned char fontdata_8x8[FONTDATAMAX] = {
-
+static struct font_data fontdata_8x8 = {
+       { 0, 0, FONTDATAMAX, 0 }, {
        /* 0 0x00 '^@' */
        0x00, /* 00000000 */
        0x00, /* 00000000 */
@@ -2570,8 +2570,7 @@ static const unsigned char fontdata_8x8[FONTDATAMAX] = {
        0x00, /* 00000000 */
        0x00, /* 00000000 */
        0x00, /* 00000000 */
-
-};
+} };
 
 
 const struct font_desc font_vga_8x8 = {
@@ -2579,6 +2578,6 @@ const struct font_desc font_vga_8x8 = {
        .name   = "VGA8x8",
        .width  = 8,
        .height = 8,
-       .data   = fontdata_8x8,
+       .data   = fontdata_8x8.data,
        .pref   = 0,
 };

diff --git a/lib/fonts/font_acorn_8x8.c b/lib/fonts/font_acorn_8x8.c
index 0ff0e85..069b3e8 100644 (file)
--- a/lib/fonts/font_acorn_8x8.c
+++ b/lib/fonts/font_acorn_8x8.c
@@ -3,7 +3,10 @@
 
 #include <linux/font.h>
 
-static const unsigned char acorndata_8x8[] = {
+#define FONTDATAMAX 2048
+
+static struct font_data acorndata_8x8 = {
+{ 0, 0, FONTDATAMAX, 0 }, {
 /* 00 */  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* ^@ */
 /* 01 */  0x7e, 0x81, 0xa5, 0x81, 0xbd, 0x99, 0x81, 0x7e, /* ^A */
 /* 02 */  0x7e, 0xff, 0xbd, 0xff, 0xc3, 0xe7, 0xff, 0x7e, /* ^B */
@@ -260,14 +263,14 @@ static const unsigned char acorndata_8x8[] = {
 /* FD */  0x38, 0x04, 0x18, 0x20, 0x3c, 0x00, 0x00, 0x00,
 /* FE */  0x00, 0x00, 0x3c, 0x3c, 0x3c, 0x3c, 0x00, 0x00,
 /* FF */  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
-};
+} };
 
 const struct font_desc font_acorn_8x8 = {
        .idx    = ACORN8x8_IDX,
        .name   = "Acorn8x8",
        .width  = 8,
        .height = 8,
-       .data   = acorndata_8x8,
+       .data   = acorndata_8x8.data,
 #ifdef CONFIG_ARCH_ACORN
        .pref   = 20,
 #else

diff --git a/lib/fonts/font_mini_4x6.c b/lib/fonts/font_mini_4x6.c
index 838caa1..1449876 100644 (file)
--- a/lib/fonts/font_mini_4x6.c
+++ b/lib/fonts/font_mini_4x6.c
@@ -43,8 +43,8 @@ __END__;
 
 #define FONTDATAMAX 1536
 
-static const unsigned char fontdata_mini_4x6[FONTDATAMAX] = {
-
+static struct font_data fontdata_mini_4x6 = {
+       { 0, 0, FONTDATAMAX, 0 }, {
        /*{*/
                /*   Char 0: ' '  */
        0xee,   /*=  [*** ]       */
@@ -2145,14 +2145,14 @@ static const unsigned char fontdata_mini_4x6[FONTDATAMAX] = {
        0xee,   /*=   [*** ]        */
        0x00,   /*=   [    ]        */
        /*}*/
-};
+} };
 
 const struct font_desc font_mini_4x6 = {
        .idx    = MINI4x6_IDX,
        .name   = "MINI4x6",
        .width  = 4,
        .height = 6,
-       .data   = fontdata_mini_4x6,
+       .data   = fontdata_mini_4x6.data,
        .pref   = 3,
 };
 

diff --git a/lib/fonts/font_pearl_8x8.c b/lib/fonts/font_pearl_8x8.c
index b15d3c3..32d6555 100644 (file)
--- a/lib/fonts/font_pearl_8x8.c
+++ b/lib/fonts/font_pearl_8x8.c
@@ -14,8 +14,8 @@
 
 #define FONTDATAMAX 2048
 
-static const unsigned char fontdata_pearl8x8[FONTDATAMAX] = {
-
+static struct font_data fontdata_pearl8x8 = {
+   { 0, 0, FONTDATAMAX, 0 }, {
    /* 0 0x00 '^@' */
    0x00, /* 00000000 */
    0x00, /* 00000000 */
@@ -2575,14 +2575,13 @@ static const unsigned char fontdata_pearl8x8[FONTDATAMAX] = {
    0x00, /* 00000000 */
    0x00, /* 00000000 */
    0x00, /* 00000000 */
-
-};
+} };
 
 const struct font_desc font_pearl_8x8 = {
        .idx    = PEARL8x8_IDX,
        .name   = "PEARL8x8",
        .width  = 8,
        .height = 8,
-       .data   = fontdata_pearl8x8,
+       .data   = fontdata_pearl8x8.data,
        .pref   = 2,
 };

diff --git a/lib/fonts/font_sun12x22.c b/lib/fonts/font_sun12x22.c
index 955d6ee..641a6b4 100644 (file)
--- a/lib/fonts/font_sun12x22.c
+++ b/lib/fonts/font_sun12x22.c
@@ -3,8 +3,8 @@
 
 #define FONTDATAMAX 11264
 
-static const unsigned char fontdata_sun12x22[FONTDATAMAX] = {
-
+static struct font_data fontdata_sun12x22 = {
+       { 0, 0, FONTDATAMAX, 0 }, {
        /* 0 0x00 '^@' */
        0x00, 0x00, /* 000000000000 */
        0x00, 0x00, /* 000000000000 */
@@ -6148,8 +6148,7 @@ static const unsigned char fontdata_sun12x22[FONTDATAMAX] = {
        0x00, 0x00, /* 000000000000 */
        0x00, 0x00, /* 000000000000 */
        0x00, 0x00, /* 000000000000 */
-
-};
+} };
 
 
 const struct font_desc font_sun_12x22 = {
@@ -6157,7 +6156,7 @@ const struct font_desc font_sun_12x22 = {
        .name   = "SUN12x22",
        .width  = 12,
        .height = 22,
-       .data   = fontdata_sun12x22,
+       .data   = fontdata_sun12x22.data,
 #ifdef __sparc__
        .pref   = 5,
 #else

diff --git a/lib/fonts/font_sun8x16.c b/lib/fonts/font_sun8x16.c
index 03d71e5..193fe6d 100644 (file)
--- a/lib/fonts/font_sun8x16.c
+++ b/lib/fonts/font_sun8x16.c
@@ -3,7 +3,8 @@
 
 #define FONTDATAMAX 4096
 
-static const unsigned char fontdata_sun8x16[FONTDATAMAX] = {
+static struct font_data fontdata_sun8x16 = {
+{ 0, 0, FONTDATAMAX, 0 }, {
 /* */ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
 /* */ 0x00,0x00,0x7e,0x81,0xa5,0x81,0x81,0xbd,0x99,0x81,0x81,0x7e,0x00,0x00,0x00,0x00,
 /* */ 0x00,0x00,0x7e,0xff,0xdb,0xff,0xff,0xc3,0xe7,0xff,0xff,0x7e,0x00,0x00,0x00,0x00,
@@ -260,14 +261,14 @@ static const unsigned char fontdata_sun8x16[FONTDATAMAX] = {
 /* */ 0x00,0x70,0xd8,0x30,0x60,0xc8,0xf8,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
 /* */ 0x00,0x00,0x00,0x00,0x7c,0x7c,0x7c,0x7c,0x7c,0x7c,0x7c,0x00,0x00,0x00,0x00,0x00,
 /* */ 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
-};
+} };
 
 const struct font_desc font_sun_8x16 = {
        .idx    = SUN8x16_IDX,
        .name   = "SUN8x16",
        .width  = 8,
        .height = 16,
-       .data   = fontdata_sun8x16,
+       .data   = fontdata_sun8x16.data,
 #ifdef __sparc__
        .pref   = 10,
 #else

diff --git a/lib/fonts/font_ter16x32.c b/lib/fonts/font_ter16x32.c
index 3f0cf1c..91b9c28 100644 (file)
--- a/lib/fonts/font_ter16x32.c
+++ b/lib/fonts/font_ter16x32.c
@@ -4,8 +4,8 @@
 
 #define FONTDATAMAX 16384
 
-static const unsigned char fontdata_ter16x32[FONTDATAMAX] = {
-
+static struct font_data fontdata_ter16x32 = {
+       { 0, 0, FONTDATAMAX, 0 }, {
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x7f, 0xfc, 0x7f, 0xfc,
        0x70, 0x1c, 0x70, 0x1c, 0x70, 0x1c, 0x70, 0x1c,
@@ -2054,8 +2054,7 @@ static const unsigned char fontdata_ter16x32[FONTDATAMAX] = {
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 255 */
-
-};
+} };
 
 
 const struct font_desc font_ter_16x32 = {
@@ -2063,7 +2062,7 @@ const struct font_desc font_ter_16x32 = {
        .name   = "TER16x32",
        .width  = 16,
        .height = 32,
-       .data   = fontdata_ter16x32,
+       .data   = fontdata_ter16x32.data,
 #ifdef __sparc__
        .pref   = 5,
 #else