linux/fs/proc/nommu.c
Clement Calmels 1804dc6e14 /proc/self/maps doesn't display the real file offset
This addresses

	http://bugzilla.kernel.org/show_bug.cgi?id=11318

In function show_map (file: fs/proc/task_mmu.c), if vma->vm_pgoff > 2^20
than (vma->vm_pgoff << PAGE_SIZE) is greater than 2^32 (with PAGE_SIZE
equal to 4096 (i.e.  2^12).  The next seq_printf use an unsigned long for
the conversion of (vma->vm_pgoff << PAGE_SIZE), as a result the offset
value displayed in /proc/self/maps is truncated if the page offset is
greater than 2^20.

A test that shows this issue:

#define _GNU_SOURCE
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>

#define PAGE_SIZE (getpagesize())

#if __i386__
#   define U64_STR "%llx"
#elif __x86_64
#   define U64_STR "%lx"
#else
#   error "Architecture Unsupported"
#endif

int main(int argc, char *argv[])
{
	int fd;
	char *addr;
	off64_t offset = 0x10000000;
	char *filename = "/dev/zero";

	fd = open(filename, O_RDONLY);
	if (fd < 0) {
		perror("open");
		return 1;
	}

	offset *= 0x10;
	printf("offset = " U64_STR "\n", offset);

	addr = (char*)mmap64(NULL, PAGE_SIZE, PROT_READ, MAP_PRIVATE, fd,
			     offset);
	if ((void*)addr == MAP_FAILED) {
		perror("mmap64");
		return 1;
	}

	{
		FILE *fmaps;
		char *line = NULL;
		size_t len = 0;
		ssize_t read;
		size_t filename_len = strlen(filename);

		fmaps = fopen("/proc/self/maps", "r");
		if (!fmaps) {
			perror("fopen");
			return 1;
		}
		while ((read = getline(&line, &len, fmaps)) != -1) {
			if ((read > filename_len + 1)
			    && (strncmp(&line[read - filename_len - 1], filename, filename_len) == 0))
				printf("%s", line);
		}

		if (line)
			free(line);

		fclose(fmaps);
	}

	close(fd);
	return 0;
}

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Clement Calmels <cboulte@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-08-20 15:40:30 -07:00

145 lines
3.3 KiB
C

/* nommu.c: mmu-less memory info files
*
* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* 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.
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/mman.h>
#include <linux/proc_fs.h>
#include <linux/mm.h>
#include <linux/mmzone.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
#include <linux/slab.h>
#include <linux/smp.h>
#include <linux/seq_file.h>
#include <linux/hugetlb.h>
#include <linux/vmalloc.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/tlb.h>
#include <asm/div64.h>
#include "internal.h"
/*
* display a single VMA to a sequenced file
*/
int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma)
{
unsigned long ino = 0;
struct file *file;
dev_t dev = 0;
int flags, len;
flags = vma->vm_flags;
file = vma->vm_file;
if (file) {
struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
dev = inode->i_sb->s_dev;
ino = inode->i_ino;
}
seq_printf(m,
"%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
vma->vm_start,
vma->vm_end,
flags & VM_READ ? 'r' : '-',
flags & VM_WRITE ? 'w' : '-',
flags & VM_EXEC ? 'x' : '-',
flags & VM_MAYSHARE ? flags & VM_SHARED ? 'S' : 's' : 'p',
((loff_t)vma->vm_pgoff) << PAGE_SHIFT,
MAJOR(dev), MINOR(dev), ino, &len);
if (file) {
len = 25 + sizeof(void *) * 6 - len;
if (len < 1)
len = 1;
seq_printf(m, "%*c", len, ' ');
seq_path(m, &file->f_path, "");
}
seq_putc(m, '\n');
return 0;
}
/*
* display a list of all the VMAs the kernel knows about
* - nommu kernals have a single flat list
*/
static int nommu_vma_list_show(struct seq_file *m, void *v)
{
struct vm_area_struct *vma;
vma = rb_entry((struct rb_node *) v, struct vm_area_struct, vm_rb);
return nommu_vma_show(m, vma);
}
static void *nommu_vma_list_start(struct seq_file *m, loff_t *_pos)
{
struct rb_node *_rb;
loff_t pos = *_pos;
void *next = NULL;
down_read(&nommu_vma_sem);
for (_rb = rb_first(&nommu_vma_tree); _rb; _rb = rb_next(_rb)) {
if (pos == 0) {
next = _rb;
break;
}
pos--;
}
return next;
}
static void nommu_vma_list_stop(struct seq_file *m, void *v)
{
up_read(&nommu_vma_sem);
}
static void *nommu_vma_list_next(struct seq_file *m, void *v, loff_t *pos)
{
(*pos)++;
return rb_next((struct rb_node *) v);
}
static const struct seq_operations proc_nommu_vma_list_seqop = {
.start = nommu_vma_list_start,
.next = nommu_vma_list_next,
.stop = nommu_vma_list_stop,
.show = nommu_vma_list_show
};
static int proc_nommu_vma_list_open(struct inode *inode, struct file *file)
{
return seq_open(file, &proc_nommu_vma_list_seqop);
}
static const struct file_operations proc_nommu_vma_list_operations = {
.open = proc_nommu_vma_list_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
static int __init proc_nommu_init(void)
{
proc_create("maps", S_IRUGO, NULL, &proc_nommu_vma_list_operations);
return 0;
}
module_init(proc_nommu_init);