1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 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 #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 #ifdef KASAN 39 #error KASAN and DEBUG_REDZONE cannot be configured together 40 #endif 41 42 static SYSCTL_NODE(_vm, OID_AUTO, redzone, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 43 "RedZone data"); 44 static u_long redzone_extra_mem = 0; 45 SYSCTL_ULONG(_vm_redzone, OID_AUTO, extra_mem, CTLFLAG_RD, &redzone_extra_mem, 46 0, "Extra memory allocated by redzone"); 47 static int redzone_panic = 0; 48 SYSCTL_INT(_vm_redzone, OID_AUTO, panic, CTLFLAG_RWTUN, &redzone_panic, 0, 49 "Panic when buffer corruption is detected"); 50 51 #define REDZONE_CHSIZE (16) 52 #define REDZONE_CFSIZE (16) 53 #define REDZONE_HSIZE (sizeof(struct stack) + sizeof(u_long) + REDZONE_CHSIZE) 54 #define REDZONE_FSIZE (REDZONE_CFSIZE) 55 56 static u_long 57 redzone_roundup(u_long n) 58 { 59 60 if (n < REDZONE_HSIZE) 61 n = REDZONE_HSIZE; 62 if (n <= 128) 63 return (128); 64 else if (n <= 256) 65 return (256); 66 else if (n <= 512) 67 return (512); 68 else if (n <= 1024) 69 return (1024); 70 else if (n <= 2048) 71 return (2048); 72 return (PAGE_SIZE); 73 } 74 75 u_long 76 redzone_get_size(caddr_t naddr) 77 { 78 u_long nsize; 79 80 bcopy(naddr - REDZONE_CHSIZE - sizeof(u_long), &nsize, sizeof(nsize)); 81 return (nsize); 82 } 83 84 u_long 85 redzone_size_ntor(u_long nsize) 86 { 87 88 return (nsize + redzone_roundup(nsize) + REDZONE_FSIZE); 89 } 90 91 void * 92 redzone_addr_ntor(caddr_t naddr) 93 { 94 95 return (naddr - redzone_roundup(redzone_get_size(naddr))); 96 } 97 98 /* 99 * Set redzones and remember allocation backtrace. 100 */ 101 void * 102 redzone_setup(caddr_t raddr, u_long nsize) 103 { 104 struct stack st; 105 caddr_t haddr, faddr; 106 107 atomic_add_long(&redzone_extra_mem, redzone_size_ntor(nsize) - nsize); 108 109 haddr = raddr + redzone_roundup(nsize) - REDZONE_HSIZE; 110 faddr = haddr + REDZONE_HSIZE + nsize; 111 112 /* Redzone header. */ 113 stack_save(&st); 114 bcopy(&st, haddr, sizeof(st)); 115 haddr += sizeof(st); 116 bcopy(&nsize, haddr, sizeof(nsize)); 117 haddr += sizeof(nsize); 118 memset(haddr, 0x42, REDZONE_CHSIZE); 119 haddr += REDZONE_CHSIZE; 120 121 /* Redzone footer. */ 122 memset(faddr, 0x42, REDZONE_CFSIZE); 123 124 return (haddr); 125 } 126 127 /* 128 * Verify redzones. 129 * This function is called on free() and realloc(). 130 */ 131 void 132 redzone_check(caddr_t naddr) 133 { 134 struct stack ast, fst; 135 caddr_t haddr, faddr; 136 u_int ncorruptions; 137 u_long nsize; 138 int i; 139 140 haddr = naddr - REDZONE_HSIZE; 141 bcopy(haddr, &ast, sizeof(ast)); 142 haddr += sizeof(ast); 143 bcopy(haddr, &nsize, sizeof(nsize)); 144 haddr += sizeof(nsize); 145 146 atomic_subtract_long(&redzone_extra_mem, 147 redzone_size_ntor(nsize) - nsize); 148 149 /* Look for buffer underflow. */ 150 ncorruptions = 0; 151 for (i = 0; i < REDZONE_CHSIZE; i++, haddr++) { 152 if (*(u_char *)haddr != 0x42) 153 ncorruptions++; 154 } 155 if (ncorruptions > 0) { 156 printf("REDZONE: Buffer underflow detected. %u byte%s " 157 "corrupted before %p (%lu bytes allocated).\n", 158 ncorruptions, ncorruptions == 1 ? "" : "s", naddr, nsize); 159 printf("Allocation backtrace:\n"); 160 stack_print_ddb(&ast); 161 printf("Free backtrace:\n"); 162 stack_save(&fst); 163 stack_print_ddb(&fst); 164 if (redzone_panic) 165 panic("Stopping here."); 166 } 167 faddr = naddr + nsize; 168 /* Look for buffer overflow. */ 169 ncorruptions = 0; 170 for (i = 0; i < REDZONE_CFSIZE; i++, faddr++) { 171 if (*(u_char *)faddr != 0x42) 172 ncorruptions++; 173 } 174 if (ncorruptions > 0) { 175 printf("REDZONE: Buffer overflow detected. %u byte%s corrupted " 176 "after %p (%lu bytes allocated).\n", ncorruptions, 177 ncorruptions == 1 ? "" : "s", naddr + nsize, nsize); 178 printf("Allocation backtrace:\n"); 179 stack_print_ddb(&ast); 180 printf("Free backtrace:\n"); 181 stack_save(&fst); 182 stack_print_ddb(&fst); 183 if (redzone_panic) 184 panic("Stopping here."); 185 } 186 } 187