1/*-
2 * Copyright (c) 2006 Pawel Jakub Dawidek <pjd@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: releng/11.0/sys/vm/redzone.c 267992 2014-06-28 03:56:17Z hselasky $");
29
30#include <sys/param.h>
31#include <sys/systm.h>
32#include <sys/kernel.h>
33#include <sys/stack.h>
34#include <sys/sysctl.h>
35
36#include <vm/redzone.h>
37
38
39static SYSCTL_NODE(_vm, OID_AUTO, redzone, CTLFLAG_RW, NULL, "RedZone data");
40static u_long redzone_extra_mem = 0;
41SYSCTL_ULONG(_vm_redzone, OID_AUTO, extra_mem, CTLFLAG_RD, &redzone_extra_mem,
42    0, "Extra memory allocated by redzone");
43static int redzone_panic = 0;
44SYSCTL_INT(_vm_redzone, OID_AUTO, panic, CTLFLAG_RWTUN, &redzone_panic, 0,
45    "Panic when buffer corruption is detected");
46
47#define	REDZONE_CHSIZE	(16)
48#define	REDZONE_CFSIZE	(16)
49#define	REDZONE_HSIZE	(sizeof(struct stack) + sizeof(u_long) + REDZONE_CHSIZE)
50#define	REDZONE_FSIZE	(REDZONE_CFSIZE)
51
52static u_long
53redzone_roundup(u_long n)
54{
55
56	if (n < REDZONE_HSIZE)
57		n = REDZONE_HSIZE;
58	if (n <= 128)
59		return (128);
60	else if (n <= 256)
61		return (256);
62	else if (n <= 512)
63		return (512);
64	else if (n <= 1024)
65		return (1024);
66	else if (n <= 2048)
67		return (2048);
68	return (PAGE_SIZE);
69}
70
71u_long
72redzone_get_size(caddr_t naddr)
73{
74	u_long nsize;
75
76	bcopy(naddr - REDZONE_CHSIZE - sizeof(u_long), &nsize, sizeof(nsize));
77	return (nsize);
78}
79
80u_long
81redzone_size_ntor(u_long nsize)
82{
83
84	return (nsize + redzone_roundup(nsize) + REDZONE_FSIZE);
85}
86
87void *
88redzone_addr_ntor(caddr_t naddr)
89{
90
91	return (naddr - redzone_roundup(redzone_get_size(naddr)));
92}
93
94/*
95 * Set redzones and remember allocation backtrace.
96 */
97void *
98redzone_setup(caddr_t raddr, u_long nsize)
99{
100	struct stack st;
101	caddr_t haddr, faddr;
102
103	atomic_add_long(&redzone_extra_mem, redzone_size_ntor(nsize) - nsize);
104
105	haddr = raddr + redzone_roundup(nsize) - REDZONE_HSIZE;
106	faddr = haddr + REDZONE_HSIZE + nsize;
107
108	/* Redzone header. */
109	stack_save(&st);
110	bcopy(&st, haddr, sizeof(st));
111	haddr += sizeof(st);
112	bcopy(&nsize, haddr, sizeof(nsize));
113	haddr += sizeof(nsize);
114	memset(haddr, 0x42, REDZONE_CHSIZE);
115	haddr += REDZONE_CHSIZE;
116
117	/* Redzone footer. */
118	memset(faddr, 0x42, REDZONE_CFSIZE);
119
120	return (haddr);
121}
122
123/*
124 * Verify redzones.
125 * This function is called on free() and realloc().
126 */
127void
128redzone_check(caddr_t naddr)
129{
130	struct stack ast, fst;
131	caddr_t haddr, faddr;
132	u_int ncorruptions;
133	u_long nsize;
134	int i;
135
136	haddr = naddr - REDZONE_HSIZE;
137	bcopy(haddr, &ast, sizeof(ast));
138	haddr += sizeof(ast);
139	bcopy(haddr, &nsize, sizeof(nsize));
140	haddr += sizeof(nsize);
141
142	atomic_subtract_long(&redzone_extra_mem,
143	    redzone_size_ntor(nsize) - nsize);
144
145	/* Look for buffer underflow. */
146	ncorruptions = 0;
147	for (i = 0; i < REDZONE_CHSIZE; i++, haddr++) {
148		if (*(u_char *)haddr != 0x42)
149			ncorruptions++;
150	}
151	if (ncorruptions > 0) {
152		printf("REDZONE: Buffer underflow detected. %u byte%s "
153		    "corrupted before %p (%lu bytes allocated).\n",
154		    ncorruptions, ncorruptions == 1 ? "" : "s", naddr, nsize);
155		printf("Allocation backtrace:\n");
156		stack_print_ddb(&ast);
157		printf("Free backtrace:\n");
158		stack_save(&fst);
159		stack_print_ddb(&fst);
160		if (redzone_panic)
161			panic("Stopping here.");
162	}
163	faddr = naddr + nsize;
164	/* Look for buffer overflow. */
165	ncorruptions = 0;
166	for (i = 0; i < REDZONE_CFSIZE; i++, faddr++) {
167		if (*(u_char *)faddr != 0x42)
168			ncorruptions++;
169	}
170	if (ncorruptions > 0) {
171		printf("REDZONE: Buffer overflow detected. %u byte%s corrupted "
172		    "after %p (%lu bytes allocated).\n", ncorruptions,
173		    ncorruptions == 1 ? "" : "s", naddr + nsize, nsize);
174		printf("Allocation backtrace:\n");
175		stack_print_ddb(&ast);
176		printf("Free backtrace:\n");
177		stack_save(&fst);
178		stack_print_ddb(&fst);
179		if (redzone_panic)
180			panic("Stopping here.");
181	}
182}
183