Bug Summary

File:src/usr.sbin/lpr/lpd/allowedhost.c
Warning:line 222, column 10
Access to field 'ai_canonname' results in a dereference of a null pointer (loaded from variable 'res')

Annotated Source Code

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clang -cc1 -cc1 -triple amd64-unknown-openbsd7.0 -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name allowedhost.c -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model pic -pic-level 1 -pic-is-pie -mframe-pointer=all -relaxed-aliasing -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -target-feature +retpoline-indirect-calls -target-feature +retpoline-indirect-branches -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/usr/src/usr.sbin/lpr/lpd/obj -resource-dir /usr/local/lib/clang/13.0.0 -I /usr/src/usr.sbin/lpr/lpd/../common_source -internal-isystem /usr/local/lib/clang/13.0.0/include -internal-externc-isystem /usr/include -O2 -fdebug-compilation-dir=/usr/src/usr.sbin/lpr/lpd/obj -ferror-limit 19 -fwrapv -D_RET_PROTECTOR -ret-protector -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-valloc -fno-builtin-free -fno-builtin-strdup -fno-builtin-strndup -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /home/ben/Projects/vmm/scan-build/2022-01-12-194120-40624-1 -x c /usr/src/usr.sbin/lpr/lpd/allowedhost.c
1/*
2 * Copyright (c) 1995, 1996, 1998 Theo de Raadt. All rights reserved.
3 * Copyright (c) 1983, 1993, 1994
4 * The Regents of the University of California. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the University nor the names of its contributors
15 * may be used to endorse or promote products derived from this software
16 * without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31#include <sys/socket.h>
32#include <sys/types.h>
33
34#include <netinet/in.h>
35#include <arpa/inet.h>
36
37#include <ctype.h>
38#include <limits.h>
39#include <netdb.h>
40#include <netgroup.h>
41#include <signal.h>
42#include <stdio.h>
43#include <stdlib.h>
44#include <string.h>
45#include <syslog.h>
46#include <unistd.h>
47
48static int checkhost(struct sockaddr *, socklen_t, const char *);
49static char *gethostloop(struct sockaddr *, socklen_t);
50
51/*
52 * Check whether the specified addr is listed in hostf.
53 * Returns 0 if allowed, else -1.
54 */
55int
56allowedhost(FILE *hostf, struct sockaddr *raddr, socklen_t salen)
57{
58 char *cp, *ep, *line = NULL((void *)0);
59 char *ahost, *rhost = (char *)-1;
60 char domain[HOST_NAME_MAX255+1];
61 size_t linesize = 0;
62 ssize_t linelen;
63 int hostok = 0;
64
65 getdomainname(domain, sizeof(domain));
66
67 while ((linelen = getline(&line, &linesize, hostf)) != -1) {
1
Assuming the condition is true
→
2
←
Loop condition is true. Entering loop body
→
68 cp = line;
69 ep = line + linelen;
70 if (*cp == '#')
3
←
Assuming the condition is false
→
4
←
Taking false branch
→
71 continue;
72 while (cp < ep && !isspace((unsigned char)*cp)) {
5
←
Assuming 'cp' is < 'ep'
→
6
←
Loop condition is true. Entering loop body
→
9
←
Assuming 'cp' is < 'ep'
→
10
←
Loop condition is true. Entering loop body
→
13
←
Assuming 'cp' is >= 'ep'
→
73 if (!isprint((unsigned char)*cp))
7
←
Taking false branch
→
11
←
Taking false branch
→
74 goto bail;
75 *cp = isupper((unsigned char)*cp) ?
8
←
'?' condition is false
→
12
←
'?' condition is true
→
76 tolower((unsigned char)*cp) : *cp;
77 cp++;
78 }
79 if (cp
13.1
'cp' is not equal to 'line'
 == line)
14
←
Taking false branch
→
80 continue;
81 *cp = '\0';
82
83 ahost = line;
84 if (strlen(ahost) > HOST_NAME_MAX255)
15
←
Assuming the condition is false
→
16
←
Taking false branch
→
85 continue;
86
87 /*
88 * innetgr() must lookup a hostname (we do not attempt
89 * to change the semantics so that netgroups may have
90 * #.#.#.# addresses in the list.)
91 */
92 switch (ahost[0]) {
17
←
Control jumps to 'case 45:' at line 94
→
93 case '+':
94 case '-':
95 switch (ahost[1]) {
18
←
Control jumps to 'case 64:' at line 99
→
96 case '\0':
97 hostok = 1;
98 break;
99 case '@':
100 if (rhost == (char *)-1)
19
←
Taking true branch
→
101 rhost = gethostloop(raddr, salen);
20
←
Calling 'gethostloop'
→
102 hostok = 0;
103 if (rhost)
104 hostok = innetgr(&ahost[2], rhost,
105 NULL((void *)0), domain);
106 break;
107 default:
108 hostok = checkhost(raddr, salen, &ahost[1]);
109 break;
110 }
111 if (ahost[0] == '-')
112 hostok = -hostok;
113 break;
114 default:
115 hostok = checkhost(raddr, salen, ahost);
116 break;
117 }
118
119 /* Check if we got a match (positive or negative). */
120 if (hostok != 0)
121 break;
122 }
123bail:
124 free(line);
125 return (hostok > 0 ? 0 : -1);
126}
127
128/*
129 * Returns 1 if match, 0 if no match. If we do not find any
130 * semblance of an A->PTR->A loop, allow a simple #.#.#.# match to work.
131 */
132static int
133checkhost(struct sockaddr *raddr, socklen_t salen, const char *lhost)
134{
135 struct addrinfo hints, *res, *r;
136 char h1[NI_MAXHOST256], h2[NI_MAXHOST256];
137 int error;
138 const int niflags = NI_NUMERICHOST1;
139
140 h1[0] = '\0';
141 if (getnameinfo(raddr, salen, h1, sizeof(h1), NULL((void *)0), 0, niflags) != 0)
142 return (0);
143
144 /* Resolve laddr into sockaddr */
145 memset(&hints, 0, sizeof(hints));
146 hints.ai_family = raddr->sa_family;
147 hints.ai_socktype = SOCK_DGRAM2; /*dummy*/
148 res = NULL((void *)0);
149 error = getaddrinfo(lhost, "0", &hints, &res);
150 if (error)
151 return (0);
152
153 /*
154 * Try string comparisons between raddr and laddr.
155 */
156 for (r = res; r; r = r->ai_next) {
157 h2[0] = '\0';
158 if (getnameinfo(r->ai_addr, r->ai_addrlen, h2, sizeof(h2),
159 NULL((void *)0), 0, niflags) != 0)
160 continue;
161 if (strcasecmp(h1, h2) == 0) {
162 freeaddrinfo(res);
163 return (1);
164 }
165 }
166
167 /* No match. */
168 freeaddrinfo(res);
169 return (0);
170}
171
172/*
173 * Return the hostname associated with the supplied address.
174 * Do a reverse lookup as well for security. If a loop cannot
175 * be found, pack the result of inet_ntoa() into the string.
176 */
177static char *
178gethostloop(struct sockaddr *raddr, socklen_t salen)
179{
180 static char remotehost[NI_MAXHOST256];
181 char h1[NI_MAXHOST256], h2[NI_MAXHOST256];
182 struct addrinfo hints, *res, *r;
183 int error;
184 const int niflags = NI_NUMERICHOST1;
185
186 h1[0] = remotehost[0] = '\0';
187 if (getnameinfo(raddr, salen, remotehost, sizeof(remotehost),
21
←
Assuming the condition is false
→
22
←
Taking false branch
→
188 NULL((void *)0), 0, NI_NAMEREQD8) != 0)
189 return (NULL((void *)0));
190 if (getnameinfo(raddr, salen, h1, sizeof(h1), NULL((void *)0), 0, niflags) != 0)
23
←
Assuming the condition is false
→
24
←
Taking false branch
→
191 return (NULL((void *)0));
192
193 /*
194 * Look up the name and check that the supplied
195 * address is in the list
196 */
197 memset(&hints, 0, sizeof(hints));
198 hints.ai_family = raddr->sa_family;
199 hints.ai_socktype = SOCK_DGRAM2; /*dummy*/
200 hints.ai_flags = AI_CANONNAME2;
201 res = NULL((void *)0);
202 error = getaddrinfo(remotehost, "0", &hints, &res);
25
←
Value assigned to 'res'
→
203 if (error)
26
←
Assuming 'error' is 0
→
27
←
Taking false branch
→
204 return (NULL((void *)0));
205
206 for (r = res; r; r = r->ai_next) {
28
←
Assuming pointer value is null
→
29
←
Loop condition is false. Execution continues on line 221
→
207 h2[0] = '\0';
208 if (getnameinfo(r->ai_addr, r->ai_addrlen, h2, sizeof(h2),
209 NULL((void *)0), 0, niflags) != 0)
210 continue;
211 if (strcasecmp(h1, h2) == 0) {
212 freeaddrinfo(res);
213 return (remotehost);
214 }
215 }
216
217 /*
218 * Either the DNS adminstrator has made a configuration
219 * mistake, or someone has attempted to spoof us.
220 */
221 syslog(LOG_NOTICE5, "lpd: address %s not listed for host %s",
222 h1, res->ai_canonname ? res->ai_canonname : remotehost);
30
←
Access to field 'ai_canonname' results in a dereference of a null pointer (loaded from variable 'res')
223 freeaddrinfo(res);
224 return (NULL((void *)0));
225}
226
227#ifdef DEBUG
228int
229main(int argc, char *argv[])
230{
231 struct addrinfo hints;
232 int i;
233
234 memset(&hints, 0, sizeof(hints));
235 hints.ai_family = PF_UNSPEC0;
236 hints.ai_socktype = SOCK_STREAM1;
237
238 for (i = 1; i < argc; i++) {
239 struct addrinfo *res0;
240 int error = getaddrinfo(argv[i], NULL((void *)0), &hints, &res0);
241 if (error) {
242 printf("%s: %s\n", argv[i], gai_strerror(error));
243 continue;
244 }
245 error = allowedhost(stdin(&__sF[0]), res0->ai_addr, res0->ai_addrlen);
246 printf("%s: %s\n", argv[i], error ? "denied" : "allowed");
247 }
248 exit(0);
249}
250#endif /* DEBUG */