### Bug Summary

File: | builds/wireshark/wireshark/epan/tvbuff_lz77.c
Warning: | line 148, column 7 Potential leak of memory pointed to by 'p'

### 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_lz77.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=gnu11 -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/2026-05-08-100338-3641-1 -x c /builds/wireshark/wireshark/epan/tvbuff_lz77.c

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1 | /*
2 | * Decompression code for Plain LZ77. This encoding is used by
3 | * Microsoft in various file formats and protocols including SMB3.
4 | *
5 | * See MS-XCA.
6 | *
7 | * Copyright (C) 2019 Aurélien Aptel
8 | *
9 | * SPDX-License-Identifier: GPL-2.0-or-later
10 | */
11 |
12 | #include <glib.h>
13 | #include <epan/exceptions.h>
14 | #include <epan/tvbuff.h>
15 | #include <epan/wmem_scopes.h>
16 |
17 | #define MAX_INPUT_SIZE(16*1024*1024) (16*1024*1024) /* 16MB */
18 |
19 | static bool_Bool do_uncompress(tvbuff_t *tvb, int offset, int in_size,
20 | wmem_array_t *obuf)
21 | {
22 | unsigned buf_flags = 0, buf_flag_count = 0;
23 | int in_off = 0;
24 | int last_length_half_byte = 0;
25 | unsigned match_bytes, match_len, match_off;
26 | unsigned i;
27 |
28 | while (1) {
29 | if (buf_flag_count == 0) {
30 | buf_flags = tvb_get_letohl(tvb, offset+in_off);
31 | in_off += 4;
32 | buf_flag_count = 32;
33 | }
34 | buf_flag_count--;
35 | if ((buf_flags & (1u << buf_flag_count)) == 0) {
36 | uint8_t v = tvb_get_uint8(tvb, offset+in_off);
37 | wmem_array_append_one(obuf, v)wmem_array_append((obuf), &(v), 1);
38 | in_off++;
39 | } else {
40 | if (in_off == in_size)
41 | return true1;
42 | match_bytes = tvb_get_letohs(tvb, offset+in_off);
43 | in_off += 2;
44 | match_len = match_bytes % 8;
45 | match_off = (match_bytes/8) + 1;
46 | if (match_len == 7) {
47 | if (last_length_half_byte == 0) {
48 | match_len = tvb_get_uint8(tvb, offset+in_off);
49 | match_len = match_len % 16;
50 | last_length_half_byte = in_off;
51 | in_off++;
52 | } else {
53 | match_len = tvb_get_uint8(tvb, offset+last_length_half_byte);
54 | match_len = match_len / 16;
55 | last_length_half_byte = 0;
56 | }
57 | if (match_len == 15) {
58 | match_len = tvb_get_uint8(tvb, offset+in_off);
59 | in_off++;
60 | if (match_len == 255) {
61 | match_len = tvb_get_letohs(tvb, offset+in_off);
62 | in_off += 2;
63 | if (match_len == 0) {
64 | match_len = tvb_get_letohl(tvb, offset+in_off);
65 | in_off += 4;
66 | }
67 | if (match_len < 15+7)
68 | return false0;
69 | match_len -= (15 + 7);
70 | }
71 | match_len += 15;
72 | }
73 | match_len += 7;
74 | }
75 | /* XXX - We could instead fail inside the loops, e.g.
76 | * testing wmem_array_get_count(obuf) > MAX_INPUT_SIZE,
77 | * and return what we could decompress in a tvb with
78 | * reported length greater than captured length. */
79 | if (match_len > MAX_INPUT_SIZE(16*1024*1024))
80 | return false0;
81 | match_len += 3;
82 | /* We can copy up to match_off bytes at a time.
83 | * (The overlap handling is *not* like memmove,
84 | * see [MS-XCA] 2.4.4.) */
85 | /* wmem_array_get_count only increases, so we only need
86 | * test this once. */
87 | if (match_off > wmem_array_get_count(obuf))
88 | return false0;
89 | uint8_t *src;
90 | ws_assert(match_off != 0)do { if ((1) && !(match_off != 0)) ws_log_fatal_full( "", LOG_LEVEL_ERROR, "epan/tvbuff_lz77.c", 90, __func__, "assertion failed: %s" , "match_off != 0"); } while (0); // Guaranteed by line 45
91 | /* Must call grow first, to realloc the array first
92 | * if needed and avoid invalidating pointers returned
93 | * from wmem_array_index when appending. */
94 | if (!wmem_array_grow(obuf, match_len))
95 | return false0;
96 | for (i = 0; i < match_len / match_off; i++) {
97 | src = wmem_array_index(obuf, wmem_array_get_count(obuf) - match_off);
98 | wmem_array_append(obuf, src, match_off);
99 | }
100 | for (i *= match_off; i < match_len; i++) {
101 | src = wmem_array_index(obuf, wmem_array_get_count(obuf) - match_off);
102 | wmem_array_append(obuf, src, 1);
103 | }
104 | }
105 | }
106 |
107 | return true1;
108 | }
109 |
110 | tvbuff_t *
111 | tvb_uncompress_lz77(tvbuff_t *tvb, const unsigned offset, unsigned in_size)
112 | {
113 | volatile bool_Bool ok = false0;
114 | wmem_allocator_t *pool;
115 | wmem_array_t *obuf;
116 | tvbuff_t *out;
117 |
118 | if (!tvb)
2 | ← | Assuming 'tvb' is non-null | →
119 | return NULL((void*)0);
120 |
121 | if (!in_size || in_size > MAX_INPUT_SIZE(16*1024*1024))
3 | ← | Assuming 'in_size' is not equal to 0 | →
4 | ← | Assuming the condition is false | →
5 | ← | Taking false branch | →
122 | return NULL((void*)0);
123 |
124 | pool = wmem_allocator_new(WMEM_ALLOCATOR_SIMPLE);
125 | obuf = wmem_array_sized_new(pool, 1, in_size*2);
126 |
127 | TRY{ except_t *volatile exc; volatile int except_state = 0; static const except_id_t catch_spec[] = { { 1, 0 } }; { struct except_stacknode except_sn; struct except_catch except_ch; except_setup_try(& except_sn, &except_ch, catch_spec, 1); if (_setjmp (except_ch .except_jmp)) *(&exc) = &except_ch.except_obj; else * (&exc) = 0; if(except_state & 1) except_state |= 2; except_state &= ~1; if (except_state == 0 && exc == 0) {
6 | ← | Assuming the condition is false | →
7 | ← | Taking false branch | →
8 | ← | Taking false branch | →
9 | ← | Taking true branch | →
128 | ok = do_uncompress(tvb, offset, in_size, obuf);
129 | } CATCH_ALLif (except_state == 0 && exc != 0 && (except_state |=1)) {
130 | ok = false0;
131 | }
132 | ENDTRYif(!(except_state&1) && exc != 0) except_rethrow( exc); except_free(except_ch.except_obj.except_dyndata); except_pop (); };};
10 | ← | Taking false branch | →
133 |
134 | if (ok) {
11 | ← | Assuming 'ok' is true | →
12 | ← | Taking true branch | →
135 | /*
136 | * Cannot pass a tvb free callback that frees the wmem
137 | * pool, so we make an extra copy that uses bare
138 | * pointers. This could be optimized if tvb API had a
139 | * free pool callback of some sort.
140 | *
141 | * XXX - Maybe a tvb_set_free_cb_with_data or similar
142 | * that takes functions that take a void* userdata
143 | * parameter?
144 | */
145 | unsigned size = wmem_array_get_count(obuf);
146 | uint8_t *p = (uint8_t *)g_malloc(size);
13 | ← | Memory is allocated | →
147 | memcpy(p, wmem_array_get_raw(obuf), size);
148 | out = tvb_new_real_data(p, size, size);
14 | ← | Potential leak of memory pointed to by 'p'
149 | tvb_set_free_cb(out, g_free);
150 | } else {
151 | out = NULL((void*)0);
152 | }
153 |
154 | wmem_destroy_allocator(pool);
155 |
156 | return out;
157 | }
158 |
159 | tvbuff_t *
160 | tvb_child_uncompress_lz77(tvbuff_t *parent, tvbuff_t *tvb, const unsigned offset, unsigned in_size)
161 | {
162 | tvbuff_t *new_tvb = tvb_uncompress_lz77(tvb, offset, in_size);
1 | Calling 'tvb_uncompress_lz77' | →
163 | if (new_tvb)
164 | tvb_set_child_real_data_tvbuff(parent, new_tvb);
165 | return new_tvb;
166 | }
167 |
168 |
169 | /*
170 | * Editor modelines - https://www.wireshark.org/tools/modelines.html
171 | *
172 | * Local variables:
173 | * c-basic-offset: 8
174 | * tab-width: 8
175 | * indent-tabs-mode: t
176 | * End:
177 | *
178 | * vi: set shiftwidth=8 tabstop=8 noexpandtab:
179 | * :indentSize=8:tabSize=8:noTabs=false:
180 | */