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 | CTLFLAG_MPSAFE, NULL, 42 "RedZone data"); 43 static u_long redzone_extra_mem = 0; 44 SYSCTL_ULONG(_vm_redzone, OID_AUTO, extra_mem, CTLFLAG_RD, &redzone_extra_mem, 45 0, "Extra memory allocated by redzone"); 46 static int redzone_panic = 0; 47 SYSCTL_INT(_vm_redzone, OID_AUTO, panic, CTLFLAG_RWTUN, &redzone_panic, 0, 48 "Panic when buffer corruption is detected"); 49 50 #define REDZONE_CHSIZE (16) 51 #define REDZONE_CFSIZE (16) 52 #define REDZONE_HSIZE (sizeof(struct stack) + sizeof(u_long) + REDZONE_CHSIZE) 53 #define REDZONE_FSIZE (REDZONE_CFSIZE) 54 55 static u_long 56 redzone_roundup(u_long n) 57 { 58 59 if (n < REDZONE_HSIZE) 60 n = REDZONE_HSIZE; 61 if (n <= 128) 62 return (128); 63 else if (n <= 256) 64 return (256); 65 else if (n <= 512) 66 return (512); 67 else if (n <= 1024) 68 return (1024); 69 else if (n <= 2048) 70 return (2048); 71 return (PAGE_SIZE); 72 } 73 74 u_long 75 redzone_get_size(caddr_t naddr) 76 { 77 u_long nsize; 78 79 bcopy(naddr - REDZONE_CHSIZE - sizeof(u_long), &nsize, sizeof(nsize)); 80 return (nsize); 81 } 82 83 u_long 84 redzone_size_ntor(u_long nsize) 85 { 86 87 return (nsize + redzone_roundup(nsize) + REDZONE_FSIZE); 88 } 89 90 void * 91 redzone_addr_ntor(caddr_t naddr) 92 { 93 94 return (naddr - redzone_roundup(redzone_get_size(naddr))); 95 } 96 97 /* 98 * Set redzones and remember allocation backtrace. 99 */ 100 void * 101 redzone_setup(caddr_t raddr, u_long nsize) 102 { 103 struct stack st; 104 caddr_t haddr, faddr; 105 106 atomic_add_long(&redzone_extra_mem, redzone_size_ntor(nsize) - nsize); 107 108 haddr = raddr + redzone_roundup(nsize) - REDZONE_HSIZE; 109 faddr = haddr + REDZONE_HSIZE + nsize; 110 111 /* Redzone header. */ 112 stack_save(&st); 113 bcopy(&st, haddr, sizeof(st)); 114 haddr += sizeof(st); 115 bcopy(&nsize, haddr, sizeof(nsize)); 116 haddr += sizeof(nsize); 117 memset(haddr, 0x42, REDZONE_CHSIZE); 118 haddr += REDZONE_CHSIZE; 119 120 /* Redzone footer. */ 121 memset(faddr, 0x42, REDZONE_CFSIZE); 122 123 return (haddr); 124 } 125 126 /* 127 * Verify redzones. 128 * This function is called on free() and realloc(). 129 */ 130 void 131 redzone_check(caddr_t naddr) 132 { 133 struct stack ast, fst; 134 caddr_t haddr, faddr; 135 u_int ncorruptions; 136 u_long nsize; 137 int i; 138 139 haddr = naddr - REDZONE_HSIZE; 140 bcopy(haddr, &ast, sizeof(ast)); 141 haddr += sizeof(ast); 142 bcopy(haddr, &nsize, sizeof(nsize)); 143 haddr += sizeof(nsize); 144 145 atomic_subtract_long(&redzone_extra_mem, 146 redzone_size_ntor(nsize) - nsize); 147 148 /* Look for buffer underflow. */ 149 ncorruptions = 0; 150 for (i = 0; i < REDZONE_CHSIZE; i++, haddr++) { 151 if (*(u_char *)haddr != 0x42) 152 ncorruptions++; 153 } 154 if (ncorruptions > 0) { 155 printf("REDZONE: Buffer underflow detected. %u byte%s " 156 "corrupted before %p (%lu bytes allocated).\n", 157 ncorruptions, ncorruptions == 1 ? "" : "s", naddr, nsize); 158 printf("Allocation backtrace:\n"); 159 stack_print_ddb(&ast); 160 printf("Free backtrace:\n"); 161 stack_save(&fst); 162 stack_print_ddb(&fst); 163 if (redzone_panic) 164 panic("Stopping here."); 165 } 166 faddr = naddr + nsize; 167 /* Look for buffer overflow. */ 168 ncorruptions = 0; 169 for (i = 0; i < REDZONE_CFSIZE; i++, faddr++) { 170 if (*(u_char *)faddr != 0x42) 171 ncorruptions++; 172 } 173 if (ncorruptions > 0) { 174 printf("REDZONE: Buffer overflow detected. %u byte%s corrupted " 175 "after %p (%lu bytes allocated).\n", ncorruptions, 176 ncorruptions == 1 ? "" : "s", naddr + nsize, nsize); 177 printf("Allocation backtrace:\n"); 178 stack_print_ddb(&ast); 179 printf("Free backtrace:\n"); 180 stack_save(&fst); 181 stack_print_ddb(&fst); 182 if (redzone_panic) 183 panic("Stopping here."); 184 } 185 } 186