Commit 1e2af92e authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds
Browse files

[PATCH] x86: use probe_kernel_address in handle_BUG() 



Avoid possible deadlock on a BUG() inside down_write(mmap_sem).  The deadlock
can only occur if something has gone horridly wrong, because a fault here
shouldn't happen.

Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 1b79e551

arch/i386/kernel/traps.c

+4 −3
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
#include <linux/kprobes.h>

#include <linux/kexec.h>

#include <linux/unwind.h>

#include <linux/uaccess.h>



#ifdef CONFIG_EISA

#include <linux/ioport.h>
@@ -40,7 +41,6 @@ 


#include <asm/processor.h>

#include <asm/system.h>

#include <asm/uaccess.h>

#include <asm/io.h>

#include <asm/atomic.h>

#include <asm/debugreg.h>
@@ -409,7 +409,7 @@ static void handle_BUG(struct pt_regs *regs) 


	if (eip < PAGE_OFFSET)

		return;

	if (__get_user(ud2, (unsigned short __user *)eip))

	if (probe_kernel_address((unsigned short __user *)eip, ud2))

		return;

	if (ud2 != 0x0b0f)

		return;
@@ -422,7 +422,8 @@ static void handle_BUG(struct pt_regs *regs) 
		char *file;

		char c;



		if (__get_user(line, (unsigned short __user *)(eip + 2)))

		if (probe_kernel_address((unsigned short __user *)(eip + 2),

					line))

			break;

		if (__get_user(file, (char * __user *)(eip + 4)) ||

		    (unsigned long)file < PAGE_OFFSET || __get_user(c, file))