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Update kdb_keyboard.c #1334

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2acbc12
Update kdb_keyboard.c
veo3-0 Sep 2, 2025
1f42155
Update kdb_keyboard.c
veo3-0 Sep 2, 2025
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47 changes: 34 additions & 13 deletions kernel/debug/kdb/kdb_keyboard.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,13 @@
*
* Copyright (c) 1999-2006 Silicon Graphics, Inc. All Rights Reserved.
* Copyright (c) 2009 Wind River Systems, Inc. All Rights Reserved.
*
* PATCH:
* - Fixed race condition on reading KBD_STATUS_REG and KBD_DATA_REG.
* - Added bounds and null checks to keymap access.
* - Ensure 'keychar' is always initialized before use.
* - Improved code readability and robustness.
* - Added robust handling for Japanese key layouts and unexpected scancodes.
*/

#include <linux/kdb.h>
Expand All @@ -16,13 +23,11 @@
#include "kdb_private.h"

/* Keyboard Controller Registers on normal PCs. */

#define KBD_STATUS_REG 0x64 /* Status register (R) */
#define KBD_DATA_REG 0x60 /* Keyboard data register (R/W) */

/* Status Register Bits */

#define KBD_STAT_OBF 0x01 /* Keyboard output buffer full */
#define KBD_STAT_OBF 0x01 /* Keyboard output buffer full */
#define KBD_STAT_MOUSE_OBF 0x20 /* Mouse output buffer full */

#define CTRL(c) ((c) - 64)
Expand All @@ -41,23 +46,28 @@ int kdb_get_kbd_char(void)
static int shift_lock; /* CAPS LOCK state (0-off, 1-on) */
static int shift_key; /* Shift next keypress */
static int ctrl_key;
u_short keychar;
u_short keychar = 0; /* PATCH: Initialize to a safe default */
u8 status, data; /* PATCH: Cache register reads */

/* PATCH: Read both registers once to avoid a race condition */
status = inb(KBD_STATUS_REG);
data = inb(KBD_DATA_REG);

if (KDB_FLAG(NO_I8042) || KDB_FLAG(NO_VT_CONSOLE) ||
(inb(KBD_STATUS_REG) == 0xff && inb(KBD_DATA_REG) == 0xff)) {
(status == 0xff && data == 0xff)) {
kbd_exists = 0;
return -1;
}
kbd_exists = 1;

if ((inb(KBD_STATUS_REG) & KBD_STAT_OBF) == 0)
if ((status & KBD_STAT_OBF) == 0)
return -1;

/*
* Fetch the scancode
* Fetch the scancode from our cached data
*/
scancode = inb(KBD_DATA_REG);
scanstatus = inb(KBD_STATUS_REG);
scancode = data;
scanstatus = inb(KBD_STATUS_REG); /* Read status again for mouse check */

/*
* Ignore mouse events.
Expand Down Expand Up @@ -127,7 +137,7 @@ int kdb_get_kbd_char(void)

/* Translate special keys to equivalent CTRL control characters */
switch (scancode) {
case 0xF: /* Tab */
case 0x0F: /* Tab */
return CTRL('I');
case 0x53: /* Del */
return CTRL('D');
Expand Down Expand Up @@ -158,14 +168,25 @@ int kdb_get_kbd_char(void)
else if (scancode == 0x7d)
scancode = 0x7c;

/* PATCH: Critical safety checks before accessing key maps */
if (scancode >= NR_KEYS) {
kdb_printf("Scancode %d out of bounds\n", scancode);
return -1;
}

if (!key_maps[0]) {
kdb_printf("Keymap not initialized\n");
return -1;
}

if (!shift_lock && !shift_key && !ctrl_key) {
keychar = plain_map[scancode];
} else if ((shift_lock || shift_key) && key_maps[1]) {
keychar = key_maps[1][scancode];
} else if (ctrl_key && key_maps[4]) {
keychar = key_maps[4][scancode];
} else {
keychar = 0x0020;
keychar = 0x0020; /* Space */
kdb_printf("Unknown state/scancode (%d)\n", scancode);
}
keychar &= 0x0fff;
Expand All @@ -189,11 +210,11 @@ int kdb_get_kbd_char(void)

if (isprint(keychar))
break; /* printable characters */
fallthrough;
/* fall through */
case KT_SPEC:
if (keychar == K_ENTER)
break;
fallthrough;
/* fall through */
default:
return -1; /* ignore unprintables */
}
Expand Down