### Bug Summary

File: | epan/tvbuff_lz77.c
Warning: | line 124, 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/libxml2 -isystem /usr/include/lua5.4 -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-truncation -Wno-format-nonliteral -Wno-pointer-sign -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/2025-10-13-100350-3623-1 -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 | if (!tvb)
29 | return false0;
30 |
31 | if (!in_size || in_size > MAX_INPUT_SIZE(16*1024*1024))
32 | return false0;
33 |
34 | while (1) {
35 | if (buf_flag_count == 0) {
36 | buf_flags = tvb_get_letohl(tvb, offset+in_off);
37 | in_off += 4;
38 | buf_flag_count = 32;
39 | }
40 | buf_flag_count--;
41 | if ((buf_flags & (1u << buf_flag_count)) == 0) {
42 | uint8_t v = tvb_get_uint8(tvb, offset+in_off);
43 | wmem_array_append_one(obuf, v)wmem_array_append((obuf), &(v), 1);
44 | in_off++;
45 | } else {
46 | if (in_off == in_size)
47 | return true1;
48 | match_bytes = tvb_get_letohs(tvb, offset+in_off);
49 | in_off += 2;
50 | match_len = match_bytes % 8;
51 | match_off = (match_bytes/8) + 1;
52 | if (match_len == 7) {
53 | if (last_length_half_byte == 0) {
54 | match_len = tvb_get_uint8(tvb, offset+in_off);
55 | match_len = match_len % 16;
56 | last_length_half_byte = in_off;
57 | in_off++;
58 | } else {
59 | match_len = tvb_get_uint8(tvb, offset+last_length_half_byte);
60 | match_len = match_len / 16;
61 | last_length_half_byte = 0;
62 | }
63 | if (match_len == 15) {
64 | match_len = tvb_get_uint8(tvb, offset+in_off);
65 | in_off++;
66 | if (match_len == 255) {
67 | match_len = tvb_get_letohs(tvb, offset+in_off);
68 | in_off += 2;
69 | if (match_len == 0) {
70 | match_len = tvb_get_letohl(tvb, offset+in_off);
71 | in_off += 4;
72 | }
73 | if (match_len < 15+7)
74 | return false0;
75 | match_len -= (15 + 7);
76 | }
77 | match_len += 15;
78 | }
79 | match_len += 7;
80 | }
81 | match_len += 3;
82 | for (i = 0; i < match_len; i++) {
83 | uint8_t byte;
84 | if (match_off > wmem_array_get_count(obuf))
85 | return false0;
86 | if (wmem_array_try_index(obuf, wmem_array_get_count(obuf)-match_off, &byte))
87 | return false0;
88 | wmem_array_append_one(obuf, byte)wmem_array_append((obuf), &(byte), 1);
89 | }
90 | }
91 | }
92 |
93 | return true1;
94 | }
95 |
96 | tvbuff_t *
97 | tvb_uncompress_lz77(tvbuff_t *tvb, const int offset, int in_size)
98 | {
99 | volatile bool_Bool ok = false0;
100 | wmem_allocator_t *pool;
101 | wmem_array_t *obuf;
102 | tvbuff_t *out;
103 |
104 | pool = wmem_allocator_new(WMEM_ALLOCATOR_SIMPLE);
105 | obuf = wmem_array_sized_new(pool, 1, in_size*2);
106 |
107 | 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) {
2 | ← | Assuming the condition is false | →
3 | ← | Taking false branch | →
4 | ← | Taking false branch | →
5 | ← | Taking true branch | →
108 | ok = do_uncompress(tvb, offset, in_size, obuf);
109 | } CATCH_ALLif (except_state == 0 && exc != 0 && (except_state |=1)) {
110 | ok = false0;
111 | }
112 | ENDTRYif(!(except_state&1) && exc != 0) except_rethrow( exc); except_free(except_ch.except_obj.except_dyndata); except_pop (); };};
6 | ← | Taking false branch | →
113 |
114 | if (ok) {
7 | ← | Assuming 'ok' is true | →
8 | ← | Taking true branch | →
115 | /*
116 | * Cannot pass a tvb free callback that frees the wmem
117 | * pool, so we make an extra copy that uses bare
118 | * pointers. This could be optimized if tvb API had a
119 | * free pool callback of some sort.
120 | */
121 | unsigned size = wmem_array_get_count(obuf);
122 | uint8_t *p = (uint8_t *)g_malloc(size);
9 | ← | Memory is allocated | →
123 | memcpy(p, wmem_array_get_raw(obuf), size);
124 | out = tvb_new_real_data(p, size, size);
10 | ← | Potential leak of memory pointed to by 'p'
125 | tvb_set_free_cb(out, g_free);
126 | } else {
127 | out = NULL((void*)0);
128 | }
129 |
130 | wmem_destroy_allocator(pool);
131 |
132 | return out;
133 | }
134 |
135 | tvbuff_t *
136 | tvb_child_uncompress_lz77(tvbuff_t *parent, tvbuff_t *tvb, const int offset, int in_size)
137 | {
138 | tvbuff_t *new_tvb = tvb_uncompress_lz77(tvb, offset, in_size);
1 | Calling 'tvb_uncompress_lz77' | →
139 | if (new_tvb)
140 | tvb_set_child_real_data_tvbuff(parent, new_tvb);
141 | return new_tvb;
142 | }
143 |
144 |
145 | /*
146 | * Editor modelines - https://www.wireshark.org/tools/modelines.html
147 | *
148 | * Local variables:
149 | * c-basic-offset: 8
150 | * tab-width: 8
151 | * indent-tabs-mode: t
152 | * End:
153 | *
154 | * vi: set shiftwidth=8 tabstop=8 noexpandtab:
155 | * :indentSize=8:tabSize=8:noTabs=false:
156 | */