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