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[PATCH] i386: Use probe_kernel_address instead of __get_user in fault paths 

Makes the intention of the code cleaner to read and avoids
a potential deadlock on mmap_sem. Also change the types of
the arguments to not include __user because they're really
not user addresses.

Signed-off-by: Andi Kleen <ak@suse.de>
This commit is contained in:
Andi Kleen 2006-12-07 02:14:06 +01:00 committed by Andi Kleen
parent ab2bf0c1c6
commit 11a4180c0b
2 changed files with 19 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
arch/i386/kernel/traps.c
View File

@ -380,7 +380,7 @@ void show_registers(struct pt_regs *regs)
* time of the fault.. * time of the fault..
*/ */
if (in_kernel) { if (in_kernel) {
u8 __user *eip; u8 *eip;
int code_bytes = 64; int code_bytes = 64;
unsigned char c; unsigned char c;
@ -389,18 +389,20 @@ void show_registers(struct pt_regs *regs)
printk(KERN_EMERG "Code: "); printk(KERN_EMERG "Code: ");
eip = (u8 __user *)regs->eip - 43; eip = (u8 *)regs->eip - 43;
if (eip < (u8 __user *)PAGE_OFFSET || __get_user(c, eip)) { if (eip < (u8 *)PAGE_OFFSET ||
probe_kernel_address(eip, c)) {
/* try starting at EIP */ /* try starting at EIP */
eip = (u8 __user *)regs->eip; eip = (u8 *)regs->eip;
code_bytes = 32; code_bytes = 32;
} }
for (i = 0; i < code_bytes; i++, eip++) { for (i = 0; i < code_bytes; i++, eip++) {
if (eip < (u8 __user *)PAGE_OFFSET || __get_user(c, eip)) { if (eip < (u8 *)PAGE_OFFSET ||
probe_kernel_address(eip, c)) {
printk(" Bad EIP value."); printk(" Bad EIP value.");
break; break;
} }
if (eip == (u8 __user *)regs->eip) if (eip == (u8 *)regs->eip)
printk("<%02x> ", c); printk("<%02x> ", c);
else else
printk("%02x ", c); printk("%02x ", c);
@ -416,7 +418,7 @@ static void handle_BUG(struct pt_regs *regs)
if (eip < PAGE_OFFSET) if (eip < PAGE_OFFSET)
return; return;
if (probe_kernel_address((unsigned short __user *)eip, ud2)) if (probe_kernel_address((unsigned short *)eip, ud2))
return; return;
if (ud2 != 0x0b0f) if (ud2 != 0x0b0f)
return; return;
@ -429,11 +431,11 @@ static void handle_BUG(struct pt_regs *regs)
char *file; char *file;
char c; char c;
if (probe_kernel_address((unsigned short __user *)(eip + 2), if (probe_kernel_address((unsigned short *)(eip + 2), line))
line))
break; break;
if (__get_user(file, (char * __user *)(eip + 4)) || if (probe_kernel_address((char **)(eip + 4), file) ||
(unsigned long)file < PAGE_OFFSET || __get_user(c, file)) (unsigned long)file < PAGE_OFFSET ||
probe_kernel_address(file, c))
file = "<bad filename>"; file = "<bad filename>";
printk(KERN_EMERG "kernel BUG at %s:%d!\n", file, line); printk(KERN_EMERG "kernel BUG at %s:%d!\n", file, line);

12
arch/i386/mm/fault.c
View File

@ -22,9 +22,9 @@
#include <linux/highmem.h> #include <linux/highmem.h>
#include <linux/module.h> #include <linux/module.h>
#include <linux/kprobes.h> #include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <asm/system.h> #include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/desc.h> #include <asm/desc.h>
#include <asm/kdebug.h> #include <asm/kdebug.h>
#include <asm/segment.h> #include <asm/segment.h>
@ -167,7 +167,7 @@ static inline unsigned long get_segment_eip(struct pt_regs *regs,
static int __is_prefetch(struct pt_regs *regs, unsigned long addr) static int __is_prefetch(struct pt_regs *regs, unsigned long addr)
{ {
unsigned long limit; unsigned long limit;
unsigned long instr = get_segment_eip (regs, &limit); unsigned char *instr = (unsigned char *)get_segment_eip (regs, &limit);
int scan_more = 1; int scan_more = 1;
int prefetch = 0; int prefetch = 0;
int i; int i;
@ -177,9 +177,9 @@ static int __is_prefetch(struct pt_regs *regs, unsigned long addr)
unsigned char instr_hi; unsigned char instr_hi;
unsigned char instr_lo; unsigned char instr_lo;
if (instr > limit) if (instr > (unsigned char *)limit)
break; break;
if (__get_user(opcode, (unsigned char __user *) instr)) if (probe_kernel_address(instr, opcode))
break; break;
instr_hi = opcode & 0xf0; instr_hi = opcode & 0xf0;
@ -204,9 +204,9 @@ static int __is_prefetch(struct pt_regs *regs, unsigned long addr)
case 0x00: case 0x00:
/* Prefetch instruction is 0x0F0D or 0x0F18 */ /* Prefetch instruction is 0x0F0D or 0x0F18 */
scan_more = 0; scan_more = 0;
if (instr > limit) if (instr > (unsigned char *)limit)
break; break;
if (__get_user(opcode, (unsigned char __user *) instr)) if (probe_kernel_address(instr, opcode))
break; break;
prefetch = (instr_lo == 0xF) && prefetch = (instr_lo == 0xF) &&
(opcode == 0x0D || opcode == 0x18); (opcode == 0x0D || opcode == 0x18);