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 40 41 static SYSCTL_NODE(_vm, OID_AUTO, redzone, CTLFLAG_RW, NULL, "RedZone data"); 42 static u_long redzone_extra_mem = 0; 43 SYSCTL_ULONG(_vm_redzone, OID_AUTO, extra_mem, CTLFLAG_RD, &redzone_extra_mem, 44 0, "Extra memory allocated by redzone"); 45 static int redzone_panic = 0; 46 SYSCTL_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 54 static u_long 55 redzone_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 73 u_long 74 redzone_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 82 u_long 83 redzone_size_ntor(u_long nsize) 84 { 85 86 return (nsize + redzone_roundup(nsize) + REDZONE_FSIZE); 87 } 88 89 void * 90 redzone_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 */ 99 void * 100 redzone_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 */ 129 void 130 redzone_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