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int10: Do an mprotect(..,PROT_EXEC) on shmat()ed memory ranges. 

When the linux kernel sets the NX bit vm86 segfaults when it tries to execute
code in memory that is not marked EXEC. Such code gets called whenever
we return from a VBIOS call to signal the calling program that the call
is actually finished and that we are not trapping for other reasons (like
IO accesses).
Use mprotect(2) to set these memory ranges PROT_EXEC.
This commit is contained in:
Egbert Eich 2008-11-21 18:50:01 +01:00
parent a54153e669
commit a9e20306fb
1 changed files with 10 additions and 2 deletions
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12
hw/xfree86/os-support/linux/int10/linux.c
View File

@ -1,6 +1,6 @@
/*
* linux specific part of the int10 module
* Copyright 1999, 2000, 2001, 2002, 2003, 2004 Egbert Eich
* Copyright 1999, 2000, 2001, 2002, 2003, 2004, 2008 Egbert Eich
*/
#ifdef HAVE_XORG_CONFIG_H
#include <xorg-config.h>
@ -357,7 +357,10 @@ MapCurrentInt10(xf86Int10InfoPtr pInt)
"shmat(low_mem) error: %s\n",strerror(errno));
return FALSE;
}
if (mprotect((void*)0, V_RAM, PROT_READ|PROT_WRITE|PROT_EXEC) != 0)
xf86DrvMsg(pInt->scrnIndex, X_ERROR,
"Cannot set EXEC bit on low memory: %s\n", strerror(errno));
if (((linuxInt10Priv*)pInt->private)->highMem >= 0) {
addr = shmat(((linuxInt10Priv*)pInt->private)->highMem,
(char*)HIGH_MEM, 0);
@ -368,6 +371,11 @@ MapCurrentInt10(xf86Int10InfoPtr pInt)
"shmget error: %s\n",strerror(errno));
return FALSE;
}
if (mprotect((void*)HIGH_MEM, HIGH_MEM_SIZE,
PROT_READ|PROT_WRITE|PROT_EXEC) != 0)
xf86DrvMsg(pInt->scrnIndex, X_ERROR,
"Cannot set EXEC bit on high memory: %s\n",
strerror(errno));
} else {
if ((fd = open(DEV_MEM, O_RDWR, 0)) >= 0) {
if (mmap((void *)(V_BIOS), SYS_BIOS - V_BIOS,