Bug Summary

File:src/lib/libutil/login_fbtab.c
Warning:line 101, column 4
Potential leak of memory pointed to by 'buf'

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 login_fbtab.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 -fhalf-no-semantic-interposition -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/lib/libutil/obj -resource-dir /usr/local/lib/clang/13.0.0 -D PIC -internal-isystem /usr/local/lib/clang/13.0.0/include -internal-externc-isystem /usr/include -O2 -fdebug-compilation-dir=/usr/src/lib/libutil/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/lib/libutil/login_fbtab.c
1/* $OpenBSD: login_fbtab.c,v 1.16 2015/11/27 01:57:59 mmcc Exp $ */
2
3/************************************************************************
4* Copyright 1995 by Wietse Venema. All rights reserved. Some individual
5* files may be covered by other copyrights.
6*
7* This material was originally written and compiled by Wietse Venema at
8* Eindhoven University of Technology, The Netherlands, in 1990, 1991,
9* 1992, 1993, 1994 and 1995.
10*
11* Redistribution and use in source and binary forms, with or without
12* modification, are permitted provided that this entire copyright notice
13* is duplicated in all such copies.
14*
15* This software is provided "as is" and without any expressed or implied
16* warranties, including, without limitation, the implied warranties of
17* merchantibility and fitness for any particular purpose.
18************************************************************************/
19/*
20 SYNOPSIS
21 void login_fbtab(tty, uid, gid)
22 char *tty;
23 uid_t uid;
24 gid_t gid;
25
26 DESCRIPTION
27 This module implements device security as described in the
28 SunOS 4.1.x fbtab(5) and SunOS 5.x logindevperm(4) manual
29 pages. The program first looks for /etc/fbtab. If that file
30 cannot be opened it attempts to process /etc/logindevperm.
31 We expect entries with the folowing format:
32
33 Comments start with a # and extend to the end of the line.
34
35 Blank lines or lines with only a comment are ignored.
36
37 All other lines consist of three fields delimited by
38 whitespace: a login device (/dev/console), an octal
39 permission number (0600), and a ":"-delimited list of
40 devices (/dev/kbd:/dev/mouse). All device names are
41 absolute paths. A path that ends in "*" refers to all
42 directory entries except "." and "..".
43
44 If the tty argument (relative path) matches a login device
45 name (absolute path), the permissions of the devices in the
46 ":"-delimited list are set as specified in the second
47 field, and their ownership is changed to that of the uid
48 and gid arguments.
49
50 DIAGNOSTICS
51 Problems are reported via the syslog daemon with severity
52 LOG_ERR.
53
54 AUTHOR
55 Wietse Venema (wietse@wzv.win.tue.nl)
56 Eindhoven University of Technology
57 The Netherlands
58 */
59
60#include <sys/types.h>
61#include <sys/stat.h>
62
63#include <errno(*__errno()).h>
64#include <dirent.h>
65#include <limits.h>
66#include <paths.h>
67#include <stdio.h>
68#include <stdlib.h>
69#include <string.h>
70#include <syslog.h>
71#include <unistd.h>
72#include <util.h>
73
74#define _PATH_FBTAB"/etc/fbtab" "/etc/fbtab"
75
76static void login_protect(const char *, mode_t, uid_t, gid_t);
77
78#define WSPACE" \t\n" " \t\n"
79
80/*
81 * login_fbtab - apply protections specified in /etc/fbtab or logindevperm
82 */
83void
84login_fbtab(const char *tty, uid_t uid, gid_t gid)
85{
86 FILE *fp;
87 char *buf, *toklast, *tbuf, *devnam, *cp;
88 mode_t prot;
89 size_t len;
90
91 if ((fp = fopen(_PATH_FBTAB"/etc/fbtab", "r")) == NULL((void *)0))
1
Assuming the condition is false
→
2
←
Taking false branch
→
92 return;
93
94 tbuf = NULL((void *)0);
95 while ((buf = fgetln(fp, &len)) != NULL((void *)0)) {
3
←
Assuming the condition is true
→
4
←
Loop condition is true. Entering loop body
→
14
←
Assuming the condition is true
→
15
←
Loop condition is true. Entering loop body
→
96 if (buf[len - 1] == '\n')
5
←
Assuming the condition is false
→
6
←
Taking false branch
→
16
←
Assuming the condition is false
→
17
←
Taking false branch
→
97 buf[len - 1] = '\0';
98 else {
99 if ((tbuf = malloc(len + 1)) == NULL((void *)0))
7
←
Memory is allocated
→
8
←
Assuming the condition is false
→
9
←
Taking false branch
→
18
←
Assuming the condition is false
→
19
←
Taking false branch
→
100 break;
101 memcpy(tbuf, buf, len);
20
←
Potential leak of memory pointed to by 'buf'
102 tbuf[len] = '\0';
103 buf = tbuf;
104 }
105 if ((cp = strchr(buf, '#')))
10
←
Assuming 'cp' is null
→
11
←
Taking false branch
→
106 *cp = '\0'; /* strip comment */
107 if (buf[0] == '\0' ||
12
←
Assuming the condition is true
→
108 (cp = devnam = strtok_r(buf, WSPACE" \t\n", &toklast)) == NULL((void *)0))
109 continue; /* empty or comment */
13
←
 Execution continues on line 95
→
110 if (strncmp(devnam, _PATH_DEV"/dev/", sizeof(_PATH_DEV"/dev/") - 1) != 0 ||
111 (cp = strtok_r(NULL((void *)0), WSPACE" \t\n", &toklast)) == NULL((void *)0) ||
112 *cp != '0' ||
113 sscanf(cp, "%o", &prot) == 0 ||
114 prot == 0 ||
115 (prot & 0777) != prot ||
116 (cp = strtok_r(NULL((void *)0), WSPACE" \t\n", &toklast)) == NULL((void *)0)) {
117 syslog(LOG_ERR3, "%s: bad entry: %s", _PATH_FBTAB"/etc/fbtab",
118 cp ? cp : "(null)");
119 continue;
120 }
121 if (strcmp(devnam + sizeof(_PATH_DEV"/dev/") - 1, tty) == 0) {
122 for (cp = strtok_r(cp, ":", &toklast); cp != NULL((void *)0);
123 cp = strtok_r(NULL((void *)0), ":", &toklast))
124 login_protect(cp, prot, uid, gid);
125 }
126 }
127 free(tbuf);
128 fclose(fp);
129}
130
131/*
132 * login_protect - protect one device entry
133 */
134static void
135login_protect(const char *path, mode_t mask, uid_t uid, gid_t gid)
136{
137 char buf[PATH_MAX1024];
138 size_t pathlen = strlen(path);
139 DIR *dir;
140 struct dirent *ent;
141
142 if (pathlen >= sizeof(buf)) {
143 errno(*__errno()) = ENAMETOOLONG63;
144 syslog(LOG_ERR3, "%s: %s: %m", _PATH_FBTAB"/etc/fbtab", path);
145 return;
146 }
147
148 if (strcmp("/*", path + pathlen - 2) != 0) {
149 if (chmod(path, mask) && errno(*__errno()) != ENOENT2)
150 syslog(LOG_ERR3, "%s: chmod(%s): %m", _PATH_FBTAB"/etc/fbtab", path);
151 if (chown(path, uid, gid) && errno(*__errno()) != ENOENT2)
152 syslog(LOG_ERR3, "%s: chown(%s): %m", _PATH_FBTAB"/etc/fbtab", path);
153 } else {
154 /*
155 * This is a wildcard directory (/path/to/whatever/ * ).
156 * Make a copy of path without the trailing '*' (but leave
157 * the trailing '/' so we can append directory entries.)
158 */
159 memcpy(buf, path, pathlen - 1);
160 buf[pathlen - 1] = '\0';
161 if ((dir = opendir(buf)) == NULL((void *)0)) {
162 syslog(LOG_ERR3, "%s: opendir(%s): %m", _PATH_FBTAB"/etc/fbtab",
163 path);
164 return;
165 }
166
167 while ((ent = readdir(dir)) != NULL((void *)0)) {
168 if (strcmp(ent->d_name, ".") != 0 &&
169 strcmp(ent->d_name, "..") != 0) {
170 buf[pathlen - 1] = '\0';
171 if (strlcat(buf, ent->d_name, sizeof(buf))
172 >= sizeof(buf)) {
173 errno(*__errno()) = ENAMETOOLONG63;
174 syslog(LOG_ERR3, "%s: %s: %m",
175 _PATH_FBTAB"/etc/fbtab", path);
176 } else
177 login_protect(buf, mask, uid, gid);
178 }
179 }
180 closedir(dir);
181 }
182}