### Bug Summary

File: | builds/wireshark/wireshark/epan/tvbuff_zlib.c
Warning: | line 319, column 15 Potential leak of memory pointed to by 'uncompr'

### 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_zlib.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_zlib.c

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1 | /* tvbuff_zlib.c
2 | *
3 | * Copyright (c) 2000 by Gilbert Ramirez <gram@alumni.rice.edu>
4 | *
5 | * Wireshark - Network traffic analyzer
6 | * By Gerald Combs <gerald@wireshark.org>
7 | * Copyright 1998 Gerald Combs
8 | *
9 | * SPDX-License-Identifier: GPL-2.0-or-later
10 | */
11 |
12 | #include <config.h>
13 | #define WS_LOG_DOMAIN"Epan" LOG_DOMAIN_EPAN"Epan"
14 |
15 | #include <glib.h>
16 |
17 | #include <string.h>
18 | #include <wsutil/glib-compat.h>
19 | #include <wsutil/zlib_compat.h>
20 |
21 | #include "tvbuff.h"
22 | #include <wsutil/wslog.h>
23 |
24 | #ifdef USE_ZLIB_OR_ZLIBNG
25 | /*
26 | * Uncompresses a zlib compressed packet inside a message of tvb at offset with
27 | * length comprlen. Returns an uncompressed tvbuffer if uncompression
28 | * succeeded or NULL if uncompression failed.
29 | */
30 | #define TVB_Z_MIN_BUFSIZ32768 32768
31 | #define TVB_Z_MAX_BUFSIZ1048576 * 10 1048576 * 10
32 |
33 | tvbuff_t *
34 | tvb_uncompress_zlib(tvbuff_t *tvb, const unsigned offset, unsigned comprlen)
35 | {
36 | int err;
37 | /* bytes_out is an unsigned because tvb_new_real_data does not accept
38 | * more than an unsigned. */
39 | unsigned bytes_out = 0;
40 | uint8_t *compr;
41 | uint8_t *uncompr = NULL((void*)0);
42 | tvbuff_t *uncompr_tvb = NULL((void*)0);
43 | zlib_streamp strm;
44 | Bytef *strmbuf;
45 | unsigned inits_done = 0;
46 | int wbits = MAX_WBITS15;
47 | uint8_t *next;
48 | unsigned bufsiz;
49 | unsigned inflate_passes = 0;
50 | unsigned bytes_in = tvb_captured_length_remaining(tvb, offset);
51 |
52 | if (tvb == NULL((void*)0) || comprlen <= 0) {
1 | Assuming 'tvb' is not equal to NULL | →
2 | ← | Assuming 'comprlen' is > 0 | →
3 | ← | Taking false branch | →
53 | return NULL((void*)0);
54 | }
55 |
56 | compr = (uint8_t *)tvb_memdup(NULL((void*)0), tvb, offset, comprlen);
57 | if (compr == NULL((void*)0)) {
4 | ← | Assuming 'compr' is not equal to NULL | →
5 | ← | Taking false branch | →
58 | return NULL((void*)0);
59 | }
60 |
61 | /*
62 | * Assume that the uncompressed data is at least twice as big as
63 | * the compressed size.
64 | */
65 | if (ckd_mul(&bufsiz, bytes_in, 2)__builtin_mul_overflow((bytes_in), (2), (&bufsiz))) {
6 | ← | Taking true branch | →
66 | bufsiz = TVB_Z_MAX_BUFSIZ1048576 * 10;
67 | } else {
68 | bufsiz = CLAMP(bufsiz, TVB_Z_MIN_BUFSIZ, TVB_Z_MAX_BUFSIZ)(((bufsiz) > (1048576 * 10)) ? (1048576 * 10) : (((bufsiz) < (32768)) ? (32768) : (bufsiz)));
69 | }
70 |
71 | ws_debug("bufsiz: %u bytes\n", bufsiz)do { if (1) { ws_log_full("Epan", LOG_LEVEL_DEBUG, "epan/tvbuff_zlib.c" , 71, __func__, "bufsiz: %u bytes\n", bufsiz); } } while (0);
7 | ← | Taking true branch | →
8 | ← | Loop condition is false. Exiting loop | →
72 |
73 | next = compr;
74 |
75 | strm = g_new0(zlib_stream, 1)((zlib_stream *) g_malloc0_n ((1), sizeof (zlib_stream)));
76 | strm->next_in = next;
77 | strm->avail_in = comprlen;
78 |
79 | strmbuf = (Bytef *)g_malloc0(bufsiz);
80 | strm->next_out = strmbuf;
81 | strm->avail_out = bufsiz;
82 |
83 | err = ZLIB_PREFIX(inflateInit2)(strm, wbits)inflateInit2_((strm), (wbits), "1.3", (int)sizeof(z_stream));
84 | inits_done = 1;
85 | if (err != Z_OK0) {
9 | ← | Assuming 'err' is equal to Z_OK | →
10 | ← | Taking false branch | →
86 | ZLIB_PREFIX(inflateEnd)inflateEnd(strm);
87 | g_free(strm);
88 | wmem_free(NULL((void*)0), compr);
89 | g_free(strmbuf);
90 | return NULL((void*)0);
91 | }
92 |
93 | while (1) {
11 | ← | Loop condition is true. Entering loop body | →
20 | ← | Loop condition is true. Entering loop body | →
94 | memset(strmbuf, '\0', bufsiz);
95 | strm->next_out = strmbuf;
96 | strm->avail_out = bufsiz;
97 |
98 | err = ZLIB_PREFIX(inflate)inflate(strm, Z_SYNC_FLUSH2);
99 |
100 | if (err == Z_OK0 || err == Z_STREAM_END1) {
12 | ← | Assuming 'err' is equal to Z_OK | →
21 | ← | Assuming 'err' is not equal to Z_OK | →
22 | ← | Assuming 'err' is equal to Z_STREAM_END | →
23 | ← | Taking true branch | →
101 | unsigned bytes_pass = bufsiz - strm->avail_out;
102 |
103 | // This is an unsigned long, but won't overflow even
104 | // on platforms where that is 32-bit, because bufsize
105 | // is clamped, if we break when it reaches INT_MAX.
106 | if (strm->total_out > INT_MAX2147483647) {
13 | ← | Assuming field 'total_out' is <= INT_MAX | →
14 | ← | Taking false branch | →
24 | ← | Assuming field 'total_out' is <= INT_MAX | →
25 | ← | Taking false branch | →
107 | // Qt uses signed ints in various classes, so
108 | // the GUI can't really handle anything
109 | ws_debug("overflow, returning what we have")do { if (1) { ws_log_full("Epan", LOG_LEVEL_DEBUG, "epan/tvbuff_zlib.c" , 109, __func__, "overflow, returning what we have"); } } while (0);
110 | ZLIB_PREFIX(inflateEnd)inflateEnd(strm);
111 | g_free(strm);
112 | g_free(strmbuf);
113 | break;
114 | }
115 |
116 | ++inflate_passes;
117 |
118 | if (uncompr
14.1 | 'uncompr' is equal to NULL
== NULL((void*)0)) {
26 | ← | Assuming 'uncompr' is not equal to NULL | →
27 | ← | Taking false branch | →
119 | /*
120 | * This is ugly workaround for bug #6480
121 | * (https://gitlab.com/wireshark/wireshark/-/issues/6480)
122 | *
123 | * g_memdup2(..., 0) returns NULL (g_malloc(0) also)
124 | * when uncompr is NULL logic below doesn't create tvb
125 | * which is later interpreted as decompression failed.
126 | */
127 | uncompr = (uint8_t *)((bytes_pass || err != Z_STREAM_END1) ?
15 | ← | Assuming 'bytes_pass' is not equal to 0 | →
128 | g_memdup2(strmbuf, bytes_pass) :
129 | g_strdup("")g_strdup_inline (""));
130 | } else {
131 | uncompr = (uint8_t *)g_realloc(uncompr, bytes_out + bytes_pass);
28 | ← | Memory is allocated | →
132 | memcpy(uncompr + bytes_out, strmbuf, bytes_pass);
133 | }
134 |
135 | bytes_out += bytes_pass;
136 | ws_assert(bytes_out == strm->total_out)do { if ((1) && !(bytes_out == strm->total_out)) ws_log_fatal_full ("Epan", LOG_LEVEL_ERROR, "epan/tvbuff_zlib.c", 136, __func__ , "assertion failed: %s", "bytes_out == strm->total_out"); } while (0);
16 | ← | Assuming 'bytes_out' is equal to field 'total_out' | →
17 | ← | Taking false branch | →
18 | ← | Loop condition is false. Exiting loop | →
29 | ← | Assuming 'bytes_out' is equal to field 'total_out' | →
30 | ← | Taking false branch | →
31 | ← | Loop condition is false. Exiting loop | →
137 |
138 | if (err
18.1 | 'err' is not equal to Z_STREAM_END
31.1 | 'err' is equal to Z_STREAM_END
== Z_STREAM_END1) {
19 | ← | Taking false branch | →
32 | ← | Taking true branch | →
139 | ZLIB_PREFIX(inflateEnd)inflateEnd(strm);
140 | g_free(strm);
141 | g_free(strmbuf);
142 | break;
33 | ← | Execution continues on line 315 | →
143 | }
144 | } else if (err == Z_BUF_ERROR(-5)) {
145 | /*
146 | * It's possible that not enough frames were captured
147 | * to decompress this fully, so return what we've done
148 | * so far, if any.
149 | */
150 | ZLIB_PREFIX(inflateEnd)inflateEnd(strm);
151 | g_free(strm);
152 | g_free(strmbuf);
153 |
154 | if (uncompr != NULL((void*)0)) {
155 | break;
156 | } else {
157 | wmem_free(NULL((void*)0), compr);
158 | return NULL((void*)0);
159 | }
160 |
161 | } else if (err == Z_DATA_ERROR(-3) && inits_done == 1
162 | && uncompr == NULL((void*)0) && comprlen >= 2 &&
163 | (*compr == 0x1f) && (*(compr + 1) == 0x8b)) {
164 | /*
165 | * inflate() is supposed to handle both gzip and deflate
166 | * streams automatically, but in reality it doesn't
167 | * seem to handle either (at least not within the
168 | * context of an HTTP response.) We have to try
169 | * several tweaks, depending on the type of data and
170 | * version of the library installed.
171 | */
172 |
173 | /*
174 | * Gzip file format. Skip past the header, since the
175 | * fix to make it work (setting windowBits to 31)
176 | * doesn't work with all versions of the library.
177 | */
178 | Bytef *c = compr + 2;
179 | Bytef flags = 0;
180 |
181 | /* we read two bytes already (0x1f, 0x8b) and
182 | need at least Z_DEFLATED, 1 byte flags, 4
183 | bytes MTIME, 1 byte XFL, 1 byte OS */
184 | if (comprlen < 10 || *c != Z_DEFLATED8) {
185 | ZLIB_PREFIX(inflateEnd)inflateEnd(strm);
186 | g_free(strm);
187 | wmem_free(NULL((void*)0), compr);
188 | g_free(strmbuf);
189 | return NULL((void*)0);
190 | }
191 |
192 | c++;
193 | flags = *c;
194 | c++;
195 |
196 | /* Skip past the MTIME (4 bytes),
197 | XFL, and OS fields (1 byte each). */
198 | c += 6;
199 |
200 | if (flags & (1 << 2)) {
201 | /* An Extra field is present. It
202 | consists of 2 bytes xsize and xsize
203 | bytes of data.
204 | Read byte-by-byte (least significant
205 | byte first) to make sure we abort
206 | cleanly when the xsize is truncated
207 | after the first byte. */
208 | uint16_t xsize = 0;
209 |
210 | if ((unsigned)(c-compr) < comprlen) {
211 | xsize += *c;
212 | c++;
213 | }
214 | if ((unsigned)(c-compr) < comprlen) {
215 | xsize += *c << 8;
216 | c++;
217 | }
218 |
219 | c += xsize;
220 | }
221 |
222 | if (flags & (1 << 3)) {
223 | /* A null terminated filename */
224 |
225 | while ((unsigned)(c - compr) < comprlen && *c != '\0') {
226 | c++;
227 | }
228 |
229 | c++;
230 | }
231 |
232 | if (flags & (1 << 4)) {
233 | /* A null terminated comment */
234 |
235 | while ((unsigned)(c - compr) < comprlen && *c != '\0') {
236 | c++;
237 | }
238 |
239 | c++;
240 | }
241 |
242 |
243 | if ((unsigned)(c - compr) > comprlen) {
244 | ZLIB_PREFIX(inflateEnd)inflateEnd(strm);
245 | g_free(strm);
246 | wmem_free(NULL((void*)0), compr);
247 | g_free(strmbuf);
248 | return NULL((void*)0);
249 | }
250 | /* Drop gzip header */
251 | comprlen -= (unsigned)(c - compr);
252 | next = c;
253 |
254 | ZLIB_PREFIX(inflateReset)inflateReset(strm);
255 | strm->next_in = next;
256 | strm->avail_in = comprlen;
257 |
258 | ZLIB_PREFIX(inflateEnd)inflateEnd(strm);
259 | err = ZLIB_PREFIX(inflateInit2)(strm, wbits)inflateInit2_((strm), (wbits), "1.3", (int)sizeof(z_stream));
260 | inits_done++;
261 | if (err != Z_OK0) {
262 | g_free(strm);
263 | wmem_free(NULL((void*)0), compr);
264 | g_free(strmbuf);
265 | return NULL((void*)0);
266 | }
267 | } else if (err == Z_DATA_ERROR(-3) && uncompr == NULL((void*)0) &&
268 | inits_done <= 3) {
269 |
270 | /*
271 | * Re-init the stream with a negative
272 | * MAX_WBITS. This is necessary due to
273 | * some servers (Apache) not sending
274 | * the deflate header with the
275 | * content-encoded response.
276 | */
277 | wbits = -MAX_WBITS15;
278 |
279 | ZLIB_PREFIX(inflateReset)inflateReset(strm);
280 |
281 | strm->next_in = next;
282 | strm->avail_in = comprlen;
283 |
284 | ZLIB_PREFIX(inflateEnd)inflateEnd(strm);
285 | memset(strmbuf, '\0', bufsiz);
286 | strm->next_out = strmbuf;
287 | strm->avail_out = bufsiz;
288 |
289 | err = ZLIB_PREFIX(inflateInit2)(strm, wbits)inflateInit2_((strm), (wbits), "1.3", (int)sizeof(z_stream));
290 |
291 | inits_done++;
292 |
293 | if (err != Z_OK0) {
294 | g_free(strm);
295 | g_free(strmbuf);
296 | wmem_free(NULL((void*)0), compr);
297 | g_free(uncompr);
298 |
299 | return NULL((void*)0);
300 | }
301 | } else {
302 | ZLIB_PREFIX(inflateEnd)inflateEnd(strm);
303 | g_free(strm);
304 | g_free(strmbuf);
305 |
306 | if (uncompr == NULL((void*)0)) {
307 | wmem_free(NULL((void*)0), compr);
308 | return NULL((void*)0);
309 | }
310 |
311 | break;
312 | }
313 | }
314 |
315 | ws_debug("inflate() total passes: %u\n", inflate_passes)do { if (1) { ws_log_full("Epan", LOG_LEVEL_DEBUG, "epan/tvbuff_zlib.c" , 315, __func__, "inflate() total passes: %u\n", inflate_passes ); } } while (0);
34 | ← | Taking true branch | →
35 | ← | Loop condition is false. Exiting loop | →
316 | ws_debug("bytes in: %u\nbytes out: %u\n\n", bytes_in, bytes_out)do { if (1) { ws_log_full("Epan", LOG_LEVEL_DEBUG, "epan/tvbuff_zlib.c" , 316, __func__, "bytes in: %u\nbytes out: %u\n\n", bytes_in , bytes_out); } } while (0);
36 | ← | Taking true branch | →
37 | ← | Loop condition is false. Exiting loop | →
317 |
318 | if (uncompr
37.1 | 'uncompr' is not equal to NULL
!= NULL((void*)0)) {
38 | ← | Taking true branch | →
319 | uncompr_tvb = tvb_new_real_data(uncompr, bytes_out, bytes_out);
39 | ← | Potential leak of memory pointed to by 'uncompr'
320 | tvb_set_free_cb(uncompr_tvb, g_free);
321 | }
322 | wmem_free(NULL((void*)0), compr);
323 | return uncompr_tvb;
324 | }
325 | #else /* USE_ZLIB_OR_ZLIBNG */
326 | tvbuff_t *
327 | tvb_uncompress_zlib(tvbuff_t *tvb _U___attribute__((unused)), const unsigned offset _U___attribute__((unused)), unsigned comprlen _U___attribute__((unused)))
328 | {
329 | return NULL((void*)0);
330 | }
331 | #endif /* USE_ZLIB_OR_ZLIBNG */
332 |
333 | tvbuff_t *
334 | tvb_child_uncompress_zlib(tvbuff_t *parent, tvbuff_t *tvb, const unsigned offset, unsigned comprlen)
335 | {
336 | tvbuff_t *new_tvb = tvb_uncompress_zlib(tvb, offset, comprlen);
337 | if (new_tvb)
338 | tvb_set_child_real_data_tvbuff (parent, new_tvb);
339 | return new_tvb;
340 | }
341 |
342 | tvbuff_t *
343 | tvb_uncompress(tvbuff_t *tvb, const unsigned offset, unsigned comprlen)
344 | {
345 | return tvb_uncompress_zlib(tvb, offset, comprlen);
346 | }
347 |
348 | tvbuff_t *
349 | tvb_child_uncompress(tvbuff_t *parent, tvbuff_t *tvb, const unsigned offset, unsigned comprlen)
350 | {
351 | return tvb_child_uncompress_zlib(parent, tvb, offset, comprlen);
352 | }
353 |
354 | /*
355 | * Editor modelines - https://www.wireshark.org/tools/modelines.html
356 | *
357 | * Local variables:
358 | * c-basic-offset: 8
359 | * tab-width: 8
360 | * indent-tabs-mode: t
361 | * End:
362 | *
363 | * vi: set shiftwidth=8 tabstop=8 noexpandtab:
364 | * :indentSize=8:tabSize=8:noTabs=false:
365 | */