linux/arch/arm/nwfpe/fpopcode.c
Lennert Buytenhek 06c03cac94 [ARM] 3117/1: nwfpe kernel memory info leak
Patch from Lennert Buytenhek

The routine that nwfpe uses for converting floats/doubles to
extended precision fails to zero two bytes of kernel stack.  This
is not immediately obvious, as the floatx80 structure has 16 bits
of implicit padding (by design.)  These two bytes are copied to
userspace when an stfe is emulated, causing a possible info leak.

Make the padding explicit and zero it out in the relevant places.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-07 21:12:07 +00:00

91 lines
2.9 KiB
C

/*
NetWinder Floating Point Emulator
(c) Rebel.COM, 1998,1999
Direct questions, comments to Scott Bambrough <scottb@netwinder.org>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/config.h>
#include "fpa11.h"
#include "softfloat.h"
#include "fpopcode.h"
#include "fpsr.h"
#include "fpmodule.h"
#include "fpmodule.inl"
#ifdef CONFIG_FPE_NWFPE_XP
const floatx80 floatx80Constant[] = {
{ .high = 0x0000, .low = 0x0000000000000000ULL},/* extended 0.0 */
{ .high = 0x3fff, .low = 0x8000000000000000ULL},/* extended 1.0 */
{ .high = 0x4000, .low = 0x8000000000000000ULL},/* extended 2.0 */
{ .high = 0x4000, .low = 0xc000000000000000ULL},/* extended 3.0 */
{ .high = 0x4001, .low = 0x8000000000000000ULL},/* extended 4.0 */
{ .high = 0x4001, .low = 0xa000000000000000ULL},/* extended 5.0 */
{ .high = 0x3ffe, .low = 0x8000000000000000ULL},/* extended 0.5 */
{ .high = 0x4002, .low = 0xa000000000000000ULL},/* extended 10.0 */
};
#endif
const float64 float64Constant[] = {
0x0000000000000000ULL, /* double 0.0 */
0x3ff0000000000000ULL, /* double 1.0 */
0x4000000000000000ULL, /* double 2.0 */
0x4008000000000000ULL, /* double 3.0 */
0x4010000000000000ULL, /* double 4.0 */
0x4014000000000000ULL, /* double 5.0 */
0x3fe0000000000000ULL, /* double 0.5 */
0x4024000000000000ULL /* double 10.0 */
};
const float32 float32Constant[] = {
0x00000000, /* single 0.0 */
0x3f800000, /* single 1.0 */
0x40000000, /* single 2.0 */
0x40400000, /* single 3.0 */
0x40800000, /* single 4.0 */
0x40a00000, /* single 5.0 */
0x3f000000, /* single 0.5 */
0x41200000 /* single 10.0 */
};
/* condition code lookup table
index into the table is test code: EQ, NE, ... LT, GT, AL, NV
bit position in short is condition code: NZCV */
static const unsigned short aCC[16] = {
0xF0F0, // EQ == Z set
0x0F0F, // NE
0xCCCC, // CS == C set
0x3333, // CC
0xFF00, // MI == N set
0x00FF, // PL
0xAAAA, // VS == V set
0x5555, // VC
0x0C0C, // HI == C set && Z clear
0xF3F3, // LS == C clear || Z set
0xAA55, // GE == (N==V)
0x55AA, // LT == (N!=V)
0x0A05, // GT == (!Z && (N==V))
0xF5FA, // LE == (Z || (N!=V))
0xFFFF, // AL always
0 // NV
};
unsigned int checkCondition(const unsigned int opcode, const unsigned int ccodes)
{
return (aCC[opcode >> 28] >> (ccodes >> 28)) & 1;
}