### Bug Summary

File: | builds/wireshark/wireshark/epan/tvbuff_base64.c
Warning: | line 249, 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-22/lib/clang/22 -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/lua5.5 -isystem /usr/include/libxml2 -D CARES_NO_DEPRECATED -D G_DISABLE_DEPRECATED -D G_DISABLE_SINGLE_INCLUDES -D REX_API=extern -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-22/lib/clang/22/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/16/../../../../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 -fdwarf2-cfi-asm -o /builds/wireshark/wireshark/sbout/2026-08-18-100328-3660-1 -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 <wsutil/ws_padding_to.h>
17 | #include "proto.h"
18 |
19 | /* Copy of glib function modified for base64uri */
20 |
21 | static const unsigned char mime_base64uri_rank[256] = {
22 | 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
23 | 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
24 | 255,255,255,255,255,255,255,255,255,255,255, 255,255,63,255,255,
25 | 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,255,255,255, 0,255,255,
26 | 255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
27 | 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,255,255,255,255, 63,
28 | 255, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
29 | 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,255,255,255,255,255,
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 | 255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
38 | };
39 | /**
40 | * Copy of glib function modified for base64uri
41 | * g_base64uri_decode_step: (skip)
42 | * @in: (array length=len) (element-type uint8_t): binary input data
43 | * @len: max length of @in data to decode
44 | * @out: (out caller-allocates) (array) (element-type uint8_t): output buffer
45 | * @state: (inout): Saved state between steps, initialize to 0
46 | * @save: (inout): Saved state between steps, initialize to 0
47 | *
48 | * Incrementally decode a sequence of binary data from its Base-64 stringified
49 | * representation. By calling this function multiple times you can convert
50 | * data in chunks to avoid having to have the full encoded data in memory.
51 | *
52 | * The output buffer must be large enough to fit all the data that will
53 | * be written to it. Since base64 encodes 3 bytes in 4 chars you need
54 | * at least: (@len / 4) * 3 + 3 bytes (+ 3 may be needed in case of non-zero
55 | * state).
56 | *
57 | * Returns: The number of bytes of output that was written
58 | *
59 | * Since: 2.12
60 | **/
61 | static size_t
62 | g_base64uri_decode_step(const char* in,
63 | size_t len,
64 | unsigned char* out,
65 | int* state,
66 | unsigned* save)
67 | {
68 | const unsigned char* inptr;
69 | unsigned char* outptr;
70 | const unsigned char* inend;
71 | unsigned char c, rank;
72 | unsigned char last[2];
73 | unsigned int v;
74 | int i;
75 |
76 | 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 | →
77 | 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 | →
78 | 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 | →
79 | 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 | →
80 |
81 | if (len == 0)
17 | ← | Assuming 'len' is equal to 0 | →
18 | ← | Taking true branch | →
82 | return 0;
83 |
84 | inend = (const unsigned char*)in + len;
85 | outptr = out;
86 |
87 | /* convert 4 base64 bytes to 3 normal bytes */
88 | v = *save;
89 | i = *state;
90 |
91 | last[0] = last[1] = 0;
92 |
93 | /* we use the sign in the state to determine if we got a padding character
94 | in the previous sequence */
95 | if (i < 0)
96 | {
97 | i = -i;
98 | last[0] = '=';
99 | }
100 |
101 | inptr = (const unsigned char*)in;
102 | while (inptr < inend)
103 | {
104 | c = *inptr++;
105 | rank = mime_base64uri_rank[c];
106 | if (rank != 0xff)
107 | {
108 | last[1] = last[0];
109 | last[0] = c;
110 | v = (v << 6) | rank;
111 | i++;
112 | if (i == 4)
113 | {
114 | *outptr++ = v >> 16;
115 | if (last[1] != '=')
116 | *outptr++ = v >> 8;
117 | if (last[0] != '=')
118 | *outptr++ = v;
119 | i = 0;
120 | }
121 | }
122 | }
123 |
124 | *save = v;
125 | *state = last[0] == '=' ? -i : i;
126 |
127 | return outptr - out;
128 | }
129 | /**
130 | * Copy of glib function modified for base64uri
131 | * g_base64uri_decode:
132 | * @text: (not nullable): zero-terminated string with base64 text to decode
133 | * @out_len: (out): The length of the decoded data is written here
134 | *
135 | * Decode a sequence of Base-64 encoded text into binary data. Note
136 | * that the returned binary data is not necessarily zero-terminated,
137 | * so it should not be used as a character string.
138 | *
139 | * Returns: (transfer full) (array length=out_len) (element-type uint8_t):
140 | * newly allocated buffer containing the binary data
141 | * that @text represents. The returned buffer must
142 | * be freed with g_free().
143 | *
144 | * Since: 2.12
145 | */
146 | static unsigned char*
147 | g_base64uri_decode(const char* text,
148 | size_t* out_len)
149 | {
150 | const char pad[4] = "===";
151 | unsigned char* ret;
152 | size_t input_length;
153 | int state = 0;
154 | unsigned save = 0;
155 |
156 | 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 | →
157 | 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 | →
158 |
159 | /* XXX - We could just pass in the length instead of calling strlen,
160 | * which would allow using tvb_get_ptr. */
161 | input_length = strlen(text);
162 |
163 | /* In base64url padding is optional.
164 | * https://www.rfc-editor.org/info/rfc4648/#section-5
165 | * https://www.rfc-editor.org/info/rfc4648/#section-3.2
166 | *
167 | * https://www.rfc-editor.org/info/rfc4648/#section-4
168 | */
169 |
170 | /* We can use a smaller limit here, since we know the saved state is 0,
171 | +1 used to avoid calling g_malloc0(0), and hence returning NULL */
172 | /* Add an additional 1 to ensure there's enough space for the padding
173 | * omitted case. (g_base64_decode_step mentions adding + 3 in the
174 | * case of non-zero state, but that's only if the extra bytes added
175 | * in are not all '='.) */
176 | ret = (unsigned char * )g_malloc0((input_length / 4) * 3 + 2);
7 | ← | Memory is allocated | →
177 |
178 | *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' | →
179 |
180 | input_length = WS_PADDING_TO_4(input_length)((4U - ((input_length) % 4U)) % 4U);
181 | if (input_length
19.1 | 'input_length' is 0
)
20 | ← | Taking false branch | →
182 | *out_len += g_base64uri_decode_step(pad, input_length, &ret[*out_len], &state, &save);
183 |
184 | return ret;
185 | }
186 |
187 | tvbuff_t *
188 | base64_to_tvb(tvbuff_t *parent, const char *base64)
189 | {
190 | tvbuff_t *tvb;
191 | uint8_t *data;
192 | size_t len;
193 |
194 | data = g_base64_decode(base64, &len);
195 | tvb = tvb_new_child_real_data(parent, data, (unsigned)len, (unsigned)len);
196 |
197 | tvb_set_free_cb(tvb, g_free);
198 |
199 | return tvb;
200 | }
201 |
202 | tvbuff_t*
203 | base64_tvb_to_new_tvb(tvbuff_t* parent, unsigned offset, unsigned length)
204 | {
205 | tvbuff_t* tvb;
206 | uint8_t* data, *tmp;
207 | size_t len;
208 |
209 | /* g_base64_decode only requires NULL termination, not a valid UTF-8
210 | * or ASCII string (it silently skips over invalid bytes, we don't
211 | * check that either). So tvb_get_raw_bytes_as_string() would work,
212 | * but we would need to check the length before allocating the buffer
213 | * to avoid a memory leak (or push a CLEANUP function on exception).
214 | *
215 | * We could also implement our own function that took a length and
216 | * didn't require NULL termination. We could also do that by simply
217 | * calling g_base64_decode_step() directly.
218 | */
219 | tmp = tvb_get_string_enc(NULL((void*)0), parent, offset, length, ENC_ASCII0x00000000);
220 | data = g_base64_decode((const char*)tmp, &len);
221 | wmem_free(NULL((void*)0), tmp);
222 |
223 | tvb = tvb_new_child_real_data(parent, data, (unsigned)len, (unsigned)len);
224 |
225 | tvb_set_free_cb(tvb, g_free);
226 |
227 | return tvb;
228 | }
229 |
230 | tvbuff_t*
231 | base64uri_tvb_to_new_tvb(tvbuff_t* parent, unsigned offset, unsigned length)
232 | {
233 | tvbuff_t* tvb;
234 | uint8_t* data, *tmp;
235 | size_t len = 0;
236 |
237 | #if 0
238 | size_t expected_output_len;
239 | expected_output_length = (input_length / 4) * 3;
240 | /* Note that input_length % 4 == 1 represents bad input and _should_
241 | * never happen. Perhaps we should just consider it a failure. */
242 | experted_output_length += ((input_length % 4) + 1) / 2;
243 | #endif
244 |
245 | tmp = tvb_get_string_enc(NULL((void*)0), parent, offset, length, ENC_ASCII0x00000000);
246 | data = g_base64uri_decode((const char*)tmp, &len);
1 | Calling 'g_base64uri_decode' | →
21 | ← | Returned allocated memory | →
247 | wmem_free(NULL((void*)0), tmp);
248 |
249 | tvb = tvb_new_child_real_data(parent, data, (unsigned)len, (unsigned)len);
22 | ← | Potential leak of memory pointed to by 'data'
250 |
251 | tvb_set_free_cb(tvb, g_free);
252 |
253 | return tvb;
254 | }
255 | /*
256 | * Editor modelines - https://www.wireshark.org/tools/modelines.html
257 | *
258 | * Local Variables:
259 | * c-basic-offset: 2
260 | * tab-width: 8
261 | * indent-tabs-mode: nil
262 | * End:
263 | *
264 | * ex: set shiftwidth=2 tabstop=8 expandtab:
265 | * :indentSize=2:tabSize=8:noTabs=true:
266 | */