From: Andi Kleen <ak@suse.de>
Date: Thu, 7 Dec 2006 01:14:06 +0000 (+0100)
Subject: [PATCH] i386: Use probe_kernel_address instead of __get_user in fault paths
X-Git-Tag: v2.6.20-rc1~145^2^2~8^2~97
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=11a4180c0b03e2ee0c948fd8430ee092dc1625b3;p=linux-2.6

[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>
---

diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
index 237f4884a1..7b2f9f0220 100644
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -380,7 +380,7 @@ void show_registers(struct pt_regs *regs)
 	 * time of the fault..
 	 */
 	if (in_kernel) {
-		u8 __user *eip;
+		u8 *eip;
 		int code_bytes = 64;
 		unsigned char c;
 
@@ -389,18 +389,20 @@ void show_registers(struct pt_regs *regs)
 
 		printk(KERN_EMERG "Code: ");
 
-		eip = (u8 __user *)regs->eip - 43;
-		if (eip < (u8 __user *)PAGE_OFFSET || __get_user(c, eip)) {
+		eip = (u8 *)regs->eip - 43;
+		if (eip < (u8 *)PAGE_OFFSET ||
+			probe_kernel_address(eip, c)) {
 			/* try starting at EIP */
-			eip = (u8 __user *)regs->eip;
+			eip = (u8 *)regs->eip;
 			code_bytes = 32;
 		}
 		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.");
 				break;
 			}
-			if (eip == (u8 __user *)regs->eip)
+			if (eip == (u8 *)regs->eip)
 				printk("<%02x> ", c);
 			else
 				printk("%02x ", c);
@@ -416,7 +418,7 @@ static void handle_BUG(struct pt_regs *regs)
 
 	if (eip < PAGE_OFFSET)
 		return;
-	if (probe_kernel_address((unsigned short __user *)eip, ud2))
+	if (probe_kernel_address((unsigned short *)eip, ud2))
 		return;
 	if (ud2 != 0x0b0f)
 		return;
@@ -429,11 +431,11 @@ static void handle_BUG(struct pt_regs *regs)
 		char *file;
 		char c;
 
-		if (probe_kernel_address((unsigned short __user *)(eip + 2),
-					line))
+		if (probe_kernel_address((unsigned short *)(eip + 2), line))
 			break;
-		if (__get_user(file, (char * __user *)(eip + 4)) ||
-		    (unsigned long)file < PAGE_OFFSET || __get_user(c, file))
+		if (probe_kernel_address((char **)(eip + 4), file) ||
+		    (unsigned long)file < PAGE_OFFSET ||
+			probe_kernel_address(file, c))
 			file = "<bad filename>";
 
 		printk(KERN_EMERG "kernel BUG at %s:%d!\n", file, line);
diff --git a/arch/i386/mm/fault.c b/arch/i386/mm/fault.c
index 2581575786..aaaa4d225f 100644
--- a/arch/i386/mm/fault.c
+++ b/arch/i386/mm/fault.c
@@ -22,9 +22,9 @@
 #include <linux/highmem.h>
 #include <linux/module.h>
 #include <linux/kprobes.h>
+#include <linux/uaccess.h>
 
 #include <asm/system.h>
-#include <asm/uaccess.h>
 #include <asm/desc.h>
 #include <asm/kdebug.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)
 { 
 	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 prefetch = 0; 
 	int i;
@@ -177,9 +177,9 @@ static int __is_prefetch(struct pt_regs *regs, unsigned long addr)
 		unsigned char instr_hi;
 		unsigned char instr_lo;
 
-		if (instr > limit)
+		if (instr > (unsigned char *)limit)
 			break;
-		if (__get_user(opcode, (unsigned char __user *) instr))
+		if (probe_kernel_address(instr, opcode))
 			break; 
 
 		instr_hi = opcode & 0xf0; 
@@ -204,9 +204,9 @@ static int __is_prefetch(struct pt_regs *regs, unsigned long addr)
 		case 0x00:
 			/* Prefetch instruction is 0x0F0D or 0x0F18 */
 			scan_more = 0;
-			if (instr > limit)
+			if (instr > (unsigned char *)limit)
 				break;
-			if (__get_user(opcode, (unsigned char __user *) instr))
+			if (probe_kernel_address(instr, opcode))
 				break;
 			prefetch = (instr_lo == 0xF) &&
 				(opcode == 0x0D || opcode == 0x18);