1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2006 Pawel Jakub Dawidek <pjd@FreeBSD.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__FBSDID("$FreeBSD$");
31
32#include <sys/param.h>
33#include <sys/systm.h>
34#include <sys/kernel.h>
35#include <sys/stack.h>
36#include <sys/sysctl.h>
37
38#include <vm/redzone.h>
39
40static SYSCTL_NODE(_vm, OID_AUTO, redzone, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL,
41    "RedZone data");
42static u_long redzone_extra_mem = 0;
43SYSCTL_ULONG(_vm_redzone, OID_AUTO, extra_mem, CTLFLAG_RD, &redzone_extra_mem,
44    0, "Extra memory allocated by redzone");
45static int redzone_panic = 0;
46SYSCTL_INT(_vm_redzone, OID_AUTO, panic, CTLFLAG_RWTUN, &redzone_panic, 0,
47    "Panic when buffer corruption is detected");
48
49#define	REDZONE_CHSIZE	(16)
50#define	REDZONE_CFSIZE	(16)
51#define	REDZONE_HSIZE	(sizeof(struct stack) + sizeof(u_long) + REDZONE_CHSIZE)
52#define	REDZONE_FSIZE	(REDZONE_CFSIZE)
53
54static u_long
55redzone_roundup(u_long n)
56{
57
58	if (n < REDZONE_HSIZE)
59		n = REDZONE_HSIZE;
60	if (n <= 128)
61		return (128);
62	else if (n <= 256)
63		return (256);
64	else if (n <= 512)
65		return (512);
66	else if (n <= 1024)
67		return (1024);
68	else if (n <= 2048)
69		return (2048);
70	return (PAGE_SIZE);
71}
72
73u_long
74redzone_get_size(caddr_t naddr)
75{
76	u_long nsize;
77
78	bcopy(naddr - REDZONE_CHSIZE - sizeof(u_long), &nsize, sizeof(nsize));
79	return (nsize);
80}
81
82u_long
83redzone_size_ntor(u_long nsize)
84{
85
86	return (nsize + redzone_roundup(nsize) + REDZONE_FSIZE);
87}
88
89void *
90redzone_addr_ntor(caddr_t naddr)
91{
92
93	return (naddr - redzone_roundup(redzone_get_size(naddr)));
94}
95
96/*
97 * Set redzones and remember allocation backtrace.
98 */
99void *
100redzone_setup(caddr_t raddr, u_long nsize)
101{
102	struct stack st;
103	caddr_t haddr, faddr;
104
105	atomic_add_long(&redzone_extra_mem, redzone_size_ntor(nsize) - nsize);
106
107	haddr = raddr + redzone_roundup(nsize) - REDZONE_HSIZE;
108	faddr = haddr + REDZONE_HSIZE + nsize;
109
110	/* Redzone header. */
111	stack_save(&st);
112	bcopy(&st, haddr, sizeof(st));
113	haddr += sizeof(st);
114	bcopy(&nsize, haddr, sizeof(nsize));
115	haddr += sizeof(nsize);
116	memset(haddr, 0x42, REDZONE_CHSIZE);
117	haddr += REDZONE_CHSIZE;
118
119	/* Redzone footer. */
120	memset(faddr, 0x42, REDZONE_CFSIZE);
121
122	return (haddr);
123}
124
125/*
126 * Verify redzones.
127 * This function is called on free() and realloc().
128 */
129void
130redzone_check(caddr_t naddr)
131{
132	struct stack ast, fst;
133	caddr_t haddr, faddr;
134	u_int ncorruptions;
135	u_long nsize;
136	int i;
137
138	haddr = naddr - REDZONE_HSIZE;
139	bcopy(haddr, &ast, sizeof(ast));
140	haddr += sizeof(ast);
141	bcopy(haddr, &nsize, sizeof(nsize));
142	haddr += sizeof(nsize);
143
144	atomic_subtract_long(&redzone_extra_mem,
145	    redzone_size_ntor(nsize) - nsize);
146
147	/* Look for buffer underflow. */
148	ncorruptions = 0;
149	for (i = 0; i < REDZONE_CHSIZE; i++, haddr++) {
150		if (*(u_char *)haddr != 0x42)
151			ncorruptions++;
152	}
153	if (ncorruptions > 0) {
154		printf("REDZONE: Buffer underflow detected. %u byte%s "
155		    "corrupted before %p (%lu bytes allocated).\n",
156		    ncorruptions, ncorruptions == 1 ? "" : "s", naddr, nsize);
157		printf("Allocation backtrace:\n");
158		stack_print_ddb(&ast);
159		printf("Free backtrace:\n");
160		stack_save(&fst);
161		stack_print_ddb(&fst);
162		if (redzone_panic)
163			panic("Stopping here.");
164	}
165	faddr = naddr + nsize;
166	/* Look for buffer overflow. */
167	ncorruptions = 0;
168	for (i = 0; i < REDZONE_CFSIZE; i++, faddr++) {
169		if (*(u_char *)faddr != 0x42)
170			ncorruptions++;
171	}
172	if (ncorruptions > 0) {
173		printf("REDZONE: Buffer overflow detected. %u byte%s corrupted "
174		    "after %p (%lu bytes allocated).\n", ncorruptions,
175		    ncorruptions == 1 ? "" : "s", naddr + nsize, nsize);
176		printf("Allocation backtrace:\n");
177		stack_print_ddb(&ast);
178		printf("Free backtrace:\n");
179		stack_save(&fst);
180		stack_print_ddb(&fst);
181		if (redzone_panic)
182			panic("Stopping here.");
183	}
184}
185