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("$FreeBSD$"); 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 39 SYSCTL_NODE(_vm, OID_AUTO, redzone, CTLFLAG_RW, NULL, "RedZone data"); 40 static u_long redzone_extra_mem = 0; 41 SYSCTL_ULONG(_vm_redzone, OID_AUTO, extra_mem, CTLFLAG_RD, &redzone_extra_mem, 42 0, "Extra memory allocated by redzone"); 43 static int redzone_panic = 0; 44 TUNABLE_INT("vm.redzone.panic", &redzone_panic); 45 SYSCTL_INT(_vm_redzone, OID_AUTO, panic, CTLFLAG_RW, &redzone_panic, 0, 46 "Panic when buffer corruption is detected"); 47 48 #define REDZONE_CHSIZE (16) 49 #define REDZONE_CFSIZE (16) 50 #define REDZONE_HSIZE (sizeof(struct stack) + sizeof(u_long) + REDZONE_CHSIZE) 51 #define REDZONE_FSIZE (REDZONE_CFSIZE) 52 53 static u_long 54 redzone_roundup(u_long n) 55 { 56 57 if (n < REDZONE_HSIZE) 58 n = REDZONE_HSIZE; 59 if (n <= 128) 60 return (128); 61 else if (n <= 256) 62 return (256); 63 else if (n <= 512) 64 return (512); 65 else if (n <= 1024) 66 return (1024); 67 else if (n <= 2048) 68 return (2048); 69 return (PAGE_SIZE); 70 } 71 72 u_long 73 redzone_get_size(caddr_t naddr) 74 { 75 u_long nsize; 76 77 bcopy(naddr - REDZONE_CHSIZE - sizeof(u_long), &nsize, sizeof(nsize)); 78 return (nsize); 79 } 80 81 u_long 82 redzone_size_ntor(u_long nsize) 83 { 84 85 return (nsize + redzone_roundup(nsize) + REDZONE_FSIZE); 86 } 87 88 void * 89 redzone_addr_ntor(caddr_t naddr) 90 { 91 92 return (naddr - redzone_roundup(redzone_get_size(naddr))); 93 } 94 95 /* 96 * Set redzones and remember allocation backtrace. 97 */ 98 void * 99 redzone_setup(caddr_t raddr, u_long nsize) 100 { 101 struct stack st; 102 caddr_t haddr, faddr; 103 104 atomic_add_long(&redzone_extra_mem, redzone_size_ntor(nsize) - nsize); 105 106 haddr = raddr + redzone_roundup(nsize) - REDZONE_HSIZE; 107 faddr = haddr + REDZONE_HSIZE + nsize; 108 109 /* Redzone header. */ 110 stack_save(&st); 111 bcopy(&st, haddr, sizeof(st)); 112 haddr += sizeof(st); 113 bcopy(&nsize, haddr, sizeof(nsize)); 114 haddr += sizeof(nsize); 115 memset(haddr, 0x42, REDZONE_CHSIZE); 116 haddr += REDZONE_CHSIZE; 117 118 /* Redzone footer. */ 119 memset(faddr, 0x42, REDZONE_CFSIZE); 120 121 return (haddr); 122 } 123 124 /* 125 * Verify redzones. 126 * This function is called on free() and realloc(). 127 */ 128 void 129 redzone_check(caddr_t naddr) 130 { 131 struct stack ast, fst; 132 caddr_t haddr, faddr; 133 u_int ncorruptions; 134 u_long nsize; 135 int i; 136 137 haddr = naddr - REDZONE_HSIZE; 138 bcopy(haddr, &ast, sizeof(ast)); 139 haddr += sizeof(ast); 140 bcopy(haddr, &nsize, sizeof(nsize)); 141 haddr += sizeof(nsize); 142 143 atomic_subtract_long(&redzone_extra_mem, 144 redzone_size_ntor(nsize) - nsize); 145 146 /* Look for buffer underflow. */ 147 ncorruptions = 0; 148 for (i = 0; i < REDZONE_CHSIZE; i++, haddr++) { 149 if (*(u_char *)haddr != 0x42) 150 ncorruptions++; 151 } 152 if (ncorruptions > 0) { 153 printf("REDZONE: Buffer underflow detected. %u byte%s " 154 "corrupted before %p (%lu bytes allocated).\n", 155 ncorruptions, ncorruptions == 1 ? "" : "s", naddr, nsize); 156 printf("Allocation backtrace:\n"); 157 stack_print_ddb(&ast); 158 printf("Free backtrace:\n"); 159 stack_save(&fst); 160 stack_print_ddb(&fst); 161 if (redzone_panic) 162 panic("Stopping here."); 163 } 164 faddr = naddr + nsize; 165 /* Look for buffer overflow. */ 166 ncorruptions = 0; 167 for (i = 0; i < REDZONE_CFSIZE; i++, faddr++) { 168 if (*(u_char *)faddr != 0x42) 169 ncorruptions++; 170 } 171 if (ncorruptions > 0) { 172 printf("REDZONE: Buffer overflow detected. %u byte%s corrupted " 173 "after %p (%lu bytes allocated).\n", ncorruptions, 174 ncorruptions == 1 ? "" : "s", naddr + nsize, nsize); 175 printf("Allocation backtrace:\n"); 176 stack_print_ddb(&ast); 177 printf("Free backtrace:\n"); 178 stack_save(&fst); 179 stack_print_ddb(&fst); 180 if (redzone_panic) 181 panic("Stopping here."); 182 } 183 } 184