### Bug Summary

File: | builds/wireshark/wireshark/epan/tvbuff_base64.c
Warning: | line 221, column 9 Potential leak of memory pointed to by 'data'

### Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name tvbuff_base64.c -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 2 -fhalf-no-semantic-interposition -fno-delete-null-pointer-checks -mframe-pointer=all -relaxed-aliasing -fmath-errno -ffp-contract=on -fno-rounding-math -ffloat16-excess-precision=fast -fbfloat16-excess-precision=fast -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fdebug-compilation-dir=/builds/wireshark/wireshark/build -fcoverage-compilation-dir=/builds/wireshark/wireshark/build -resource-dir /usr/lib/llvm-21/lib/clang/21 -isystem /usr/include/glib-2.0 -isystem /usr/lib/x86_64-linux-gnu/glib-2.0/include -isystem /builds/wireshark/wireshark/epan -isystem /builds/wireshark/wireshark/build/epan -isystem /usr/include/mit-krb5 -isystem /usr/include/lua5.4 -isystem /usr/include/libxml2 -D G_DISABLE_DEPRECATED -D G_DISABLE_SINGLE_INCLUDES -D WS_BUILD_DLL -D WS_DEBUG -D WS_DEBUG_UTF_8 -D epan_EXPORTS -I /builds/wireshark/wireshark/build -I /builds/wireshark/wireshark -I /builds/wireshark/wireshark/include -I /builds/wireshark/wireshark/wiretap -D _GLIBCXX_ASSERTIONS -internal-isystem /usr/lib/llvm-21/lib/clang/21/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/14/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fmacro-prefix-map=/builds/wireshark/wireshark/= -fmacro-prefix-map=/builds/wireshark/wireshark/build/= -fmacro-prefix-map=../= -Wno-format-nonliteral -std=gnu17 -ferror-limit 19 -fvisibility=hidden -fwrapv -fwrapv-pointer -fstrict-flex-arrays=3 -stack-protector 2 -fstack-clash-protection -fcf-protection=full -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fexceptions -fcolor-diagnostics -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /builds/wireshark/wireshark/sbout/2026-05-20-100323-3659-1 -x c /builds/wireshark/wireshark/epan/tvbuff_base64.c

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1 | /* tvbuff_base64.c
2 | * Base-64 tvbuff implementation (based on real tvb)
3 | *
4 | * Wireshark - Network traffic analyzer
5 | * By Gerald Combs <gerald@wireshark.org>
6 | * Copyright 1998 Gerald Combs
7 | *
8 | * SPDX-License-Identifier: GPL-2.0-or-later
9 | */
10 |
11 | #include "config.h"
12 |
13 | #include <glib.h>
14 |
15 | #include <epan/tvbuff.h>
16 | #include "proto.h"
17 |
18 | /* Copy of glib function modified for base64uri */
19 |
20 | static const unsigned char mime_base64uri_rank[256] = {
21 | 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
22 | 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
23 | 255,255,255,255,255,255,255,255,255,255,255, 255,255,63,255,255,
24 | 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,255,255,255, 0,255,255,
25 | 255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
26 | 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,255,255,255,255, 63,
27 | 255, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
28 | 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,255,255,255,255,255,
29 | 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
30 | 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
31 | 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
32 | 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
33 | 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
34 | 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
35 | 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
36 | 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
37 | };
38 | /**
39 | * Copy of glib function modified for base64uri
40 | * g_base64uri_decode_step: (skip)
41 | * @in: (array length=len) (element-type uint8_t): binary input data
42 | * @len: max length of @in data to decode
43 | * @out: (out caller-allocates) (array) (element-type uint8_t): output buffer
44 | * @state: (inout): Saved state between steps, initialize to 0
45 | * @save: (inout): Saved state between steps, initialize to 0
46 | *
47 | * Incrementally decode a sequence of binary data from its Base-64 stringified
48 | * representation. By calling this function multiple times you can convert
49 | * data in chunks to avoid having to have the full encoded data in memory.
50 | *
51 | * The output buffer must be large enough to fit all the data that will
52 | * be written to it. Since base64 encodes 3 bytes in 4 chars you need
53 | * at least: (@len / 4) * 3 + 3 bytes (+ 3 may be needed in case of non-zero
54 | * state).
55 | *
56 | * Returns: The number of bytes of output that was written
57 | *
58 | * Since: 2.12
59 | **/
60 | static size_t
61 | g_base64uri_decode_step(const char* in,
62 | size_t len,
63 | unsigned char* out,
64 | int* state,
65 | unsigned* save)
66 | {
67 | const unsigned char* inptr;
68 | unsigned char* outptr;
69 | const unsigned char* inend;
70 | unsigned char c, rank;
71 | unsigned char last[2];
72 | unsigned int v;
73 | int i;
74 |
75 | g_return_val_if_fail(in != NULL || len == 0, 0)do { if ((in != ((void*)0) || len == 0)) { } else { g_return_if_fail_warning (((gchar*) 0), ((const char*) (__func__)), "in != NULL || len == 0" ); return (0); } } while (0);
9 | ← | Loop condition is false. Exiting loop | →
76 | g_return_val_if_fail(out != NULL, 0)do { if ((out != ((void*)0))) { } else { g_return_if_fail_warning (((gchar*) 0), ((const char*) (__func__)), "out != NULL"); return (0); } } while (0);
10 | ← | Assuming 'out' is not equal to null | →
11 | ← | Taking true branch | →
12 | ← | Loop condition is false. Exiting loop | →
77 | g_return_val_if_fail(state != NULL, 0)do { if ((state != ((void*)0))) { } else { g_return_if_fail_warning (((gchar*) 0), ((const char*) (__func__)), "state != NULL"); return (0); } } while (0);
13 | ← | Taking true branch | →
14 | ← | Loop condition is false. Exiting loop | →
78 | g_return_val_if_fail(save != NULL, 0)do { if ((save != ((void*)0))) { } else { g_return_if_fail_warning (((gchar*) 0), ((const char*) (__func__)), "save != NULL"); return (0); } } while (0);
15 | ← | Taking true branch | →
16 | ← | Loop condition is false. Exiting loop | →
79 |
80 | if (len == 0)
17 | ← | Assuming 'len' is equal to 0 | →
18 | ← | Taking true branch | →
81 | return 0;
82 |
83 | inend = (const unsigned char*)in + len;
84 | outptr = out;
85 |
86 | /* convert 4 base64 bytes to 3 normal bytes */
87 | v = *save;
88 | i = *state;
89 |
90 | last[0] = last[1] = 0;
91 |
92 | /* we use the sign in the state to determine if we got a padding character
93 | in the previous sequence */
94 | if (i < 0)
95 | {
96 | i = -i;
97 | last[0] = '=';
98 | }
99 |
100 | inptr = (const unsigned char*)in;
101 | while (inptr < inend)
102 | {
103 | c = *inptr++;
104 | rank = mime_base64uri_rank[c];
105 | if (rank != 0xff)
106 | {
107 | last[1] = last[0];
108 | last[0] = c;
109 | v = (v << 6) | rank;
110 | i++;
111 | if (i == 4)
112 | {
113 | *outptr++ = v >> 16;
114 | if (last[1] != '=')
115 | *outptr++ = v >> 8;
116 | if (last[0] != '=')
117 | *outptr++ = v;
118 | i = 0;
119 | }
120 | }
121 | }
122 |
123 | *save = v;
124 | *state = last[0] == '=' ? -i : i;
125 |
126 | return outptr - out;
127 | }
128 | /**
129 | * Copy of glib function modified for base64uri
130 | * g_base64uri_decode:
131 | * @text: (not nullable): zero-terminated string with base64 text to decode
132 | * @out_len: (out): The length of the decoded data is written here
133 | *
134 | * Decode a sequence of Base-64 encoded text into binary data. Note
135 | * that the returned binary data is not necessarily zero-terminated,
136 | * so it should not be used as a character string.
137 | *
138 | * Returns: (transfer full) (array length=out_len) (element-type uint8_t):
139 | * newly allocated buffer containing the binary data
140 | * that @text represents. The returned buffer must
141 | * be freed with g_free().
142 | *
143 | * Since: 2.12
144 | */
145 | static unsigned char*
146 | g_base64uri_decode(const char* text,
147 | size_t* out_len)
148 | {
149 | unsigned char* ret;
150 | size_t input_length;
151 | int state = 0;
152 | unsigned save = 0;
153 |
154 | g_return_val_if_fail(text != NULL, NULL)do { if ((text != ((void*)0))) { } else { g_return_if_fail_warning (((gchar*) 0), ((const char*) (__func__)), "text != NULL"); return (((void*)0)); } } while (0);
2 | ← | Assuming 'text' is not equal to null | →
3 | ← | Taking true branch | →
4 | ← | Loop condition is false. Exiting loop | →
155 | g_return_val_if_fail(out_len != NULL, NULL)do { if ((out_len != ((void*)0))) { } else { g_return_if_fail_warning (((gchar*) 0), ((const char*) (__func__)), "out_len != NULL" ); return (((void*)0)); } } while (0);
5 | ← | Taking true branch | →
6 | ← | Loop condition is false. Exiting loop | →
156 |
157 | input_length = strlen(text);
158 |
159 | /* We can use a smaller limit here, since we know the saved state is 0,
160 | +1 used to avoid calling g_malloc0(0), and hence returning NULL */
161 | ret = (unsigned char * )g_malloc0((input_length / 4) * 3 + 1);
7 | ← | Memory is allocated | →
162 |
163 | *out_len = g_base64uri_decode_step(text, input_length, ret, &state, &save);
8 | ← | Calling 'g_base64uri_decode_step' | →
19 | ← | Returning from 'g_base64uri_decode_step' | →
164 |
165 | return ret;
166 | }
167 |
168 | tvbuff_t *
169 | base64_to_tvb(tvbuff_t *parent, const char *base64)
170 | {
171 | tvbuff_t *tvb;
172 | uint8_t *data;
173 | size_t len;
174 |
175 | data = g_base64_decode(base64, &len);
176 | tvb = tvb_new_child_real_data(parent, data, (unsigned)len, (unsigned)len);
177 |
178 | tvb_set_free_cb(tvb, g_free);
179 |
180 | return tvb;
181 | }
182 |
183 | tvbuff_t*
184 | base64_tvb_to_new_tvb(tvbuff_t* parent, unsigned offset, unsigned length)
185 | {
186 | tvbuff_t* tvb;
187 | uint8_t* data, *tmp;
188 | size_t len;
189 |
190 | /* g_base64_decode only requires NULL termination, not a valid UTF-8
191 | * or ASCII string (it silently skips over invalid bytes, we don't
192 | * check that either). So tvb_get_raw_bytes_as_string() would work,
193 | * but we would need to check the length before allocating the buffer
194 | * to avoid a memory leak (or push a CLEANUP function on exception).
195 | *
196 | * We could also implement our own function that took a length and
197 | * didn't require NULL termination.
198 | */
199 | tmp = tvb_get_string_enc(NULL((void*)0), parent, offset, length, ENC_ASCII0x00000000);
200 | data = g_base64_decode((const char*)tmp, &len);
201 | wmem_free(NULL((void*)0), tmp);
202 |
203 | tvb = tvb_new_child_real_data(parent, data, (unsigned)len, (unsigned)len);
204 |
205 | tvb_set_free_cb(tvb, g_free);
206 |
207 | return tvb;
208 | }
209 |
210 | tvbuff_t*
211 | base64uri_tvb_to_new_tvb(tvbuff_t* parent, unsigned offset, unsigned length)
212 | {
213 | tvbuff_t* tvb;
214 | uint8_t* data, *tmp;
215 | size_t len = 0;
216 |
217 | tmp = tvb_get_string_enc(NULL((void*)0), parent, offset, length, ENC_ASCII0x00000000);
218 | data = g_base64uri_decode((const char*)tmp, &len);
1 | Calling 'g_base64uri_decode' | →
20 | ← | Returned allocated memory | →
219 | wmem_free(NULL((void*)0), tmp);
220 |
221 | tvb = tvb_new_child_real_data(parent, data, (unsigned)len, (unsigned)len);
21 | ← | Potential leak of memory pointed to by 'data'
222 |
223 | tvb_set_free_cb(tvb, g_free);
224 |
225 | return tvb;
226 | }
227 | /*
228 | * Editor modelines - https://www.wireshark.org/tools/modelines.html
229 | *
230 | * Local Variables:
231 | * c-basic-offset: 2
232 | * tab-width: 8
233 | * indent-tabs-mode: nil
234 | * End:
235 | *
236 | * ex: set shiftwidth=2 tabstop=8 expandtab:
237 | * :indentSize=2:tabSize=8:noTabs=true:
238 | */