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