### Bug Summary

File: | builds/wireshark/wireshark/epan/tvbuff_lznt1.c
Warning: | line 154, 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_lznt1.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/2026-08-07-100414-3660-1 -x c /builds/wireshark/wireshark/epan/tvbuff_lznt1.c

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1 | /*
2 | * Decompression code for LZNT1. 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 | * Wireshark - Network traffic analyzer
10 | * By Gerald Combs <gerald@wireshark.org>
11 | * Copyright 1998 Gerald Combs
12 | *
13 | * SPDX-License-Identifier: GPL-2.0-or-later
14 | */
15 |
16 | #include <glib.h>
17 | #include <epan/exceptions.h>
18 | #include <epan/tvbuff.h>
19 | #include <epan/wmem_scopes.h>
20 |
21 | #define MAX_INPUT_SIZE(16*1024*1024) (16*1024*1024) /* 16MB */
22 |
23 | static bool_Bool
24 | uncompress_chunk(tvbuff_t *tvb, int offset, unsigned in_size, wmem_array_t *obuf)
25 | {
26 | unsigned in_off = 0, out_off = 0, out_start = 0;
27 | uint8_t flags;
28 | unsigned i, j, val, pos;
29 |
30 | out_start = wmem_array_get_count(obuf);
31 |
32 | while (in_off < in_size) {
33 | flags = tvb_get_uint8(tvb, offset+in_off);
34 | in_off++;
35 | for (i = 0; i < 8; i++) {
36 | if (0 == ((flags>>i)&1)) {
37 | val = tvb_get_uint8(tvb, offset+in_off);
38 | in_off++;
39 | wmem_array_append_one(obuf, val)wmem_array_append((obuf), &(val), 1);
40 | out_off++;
41 | } else {
42 | unsigned f, l_mask = 0x0FFF, o_shift = 12;
43 | unsigned match_len, match_off;
44 |
45 | f = tvb_get_letohs(tvb, offset+in_off);
46 | in_off += 2;
47 | /* Let M be the largest value in [4...12] such
48 | * that 2^{M-1} < U, or 4 if there is no such.
49 | * Equivalently, we can repeatedly divide U by
50 | * 2, but we need to subtract 1 first and test
51 | * vs a weak inequality in order to account for
52 | * truncation. (But don't overflow at U == 0.)
53 | */
54 | if (out_off > 0) {
55 | pos = out_off-1;
56 | while (pos >= 0x10) {
57 | l_mask >>= 1;
58 | o_shift -= 1;
59 | pos >>= 1;
60 | }
61 | }
62 |
63 | match_len = (f & l_mask) + 3;
64 | match_off = (f >> o_shift) + 1;
65 | /* out_off only increases, only test once. */
66 | if (match_off > out_start + out_off)
67 | return false0;
68 | /* Must call grow first, to realloc the array
69 | * if needed. */
70 | if (!wmem_array_grow(obuf, match_len))
71 | return false0;
72 | uint8_t *src;
73 | for (j = 0; j < match_len / match_off; j++) {
74 | src = wmem_array_index(obuf, out_start + out_off - match_off);
75 | wmem_array_append(obuf, src, match_off);
76 | out_off += match_off;
77 | }
78 | for (j *= match_off; j < match_len; j++) {
79 | src = wmem_array_index(obuf, out_start + out_off - match_off);
80 | wmem_array_append(obuf, src, 1);
81 | out_off++;
82 | }
83 | }
84 | if (in_off == in_size) {
85 | goto out;
86 | }
87 | }
88 | }
89 | out:
90 | return true1;
91 | }
92 |
93 | static bool_Bool
94 | do_uncompress(tvbuff_t *tvb, int offset, int in_size, wmem_array_t *obuf)
95 | {
96 | int in_off = 0;
97 | uint32_t header, length, i;
98 | bool_Bool ok;
99 |
100 | if (!tvb)
101 | return false0;
102 |
103 | if (!in_size || in_size > MAX_INPUT_SIZE(16*1024*1024))
104 | return false0;
105 |
106 | while (in_off < in_size) {
107 | header = tvb_get_letohs(tvb, offset+in_off);
108 | in_off += 2;
109 | length = (header & 0x0FFF) + 1;
110 | if (!(header & 0x8000)) {
111 | for (i = 0; i < length; i++) {
112 | uint8_t v = tvb_get_uint8(tvb, offset+in_off);
113 | wmem_array_append_one(obuf, v)wmem_array_append((obuf), &(v), 1);
114 | in_off++;
115 | }
116 | } else {
117 | ok = uncompress_chunk(tvb, offset + in_off, length, obuf);
118 | if (!ok)
119 | return false0;
120 | in_off += length;
121 | }
122 | }
123 | return true1;
124 | }
125 |
126 | tvbuff_t *
127 | tvb_uncompress_lznt1(tvbuff_t *tvb, const unsigned offset, unsigned in_size)
128 | {
129 | volatile bool_Bool ok = false0;
130 | wmem_allocator_t *pool;
131 | wmem_array_t *obuf;
132 | tvbuff_t *out;
133 |
134 | pool = wmem_allocator_new(WMEM_ALLOCATOR_SIMPLE);
135 | obuf = wmem_array_sized_new(pool, 1, in_size*2);
136 |
137 | 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 | →
138 | ok = do_uncompress(tvb, offset, in_size, obuf);
139 | } CATCH_ALLif (except_state == 0 && exc != 0 && (except_state |=1)) {
140 | ok = false0;
141 | }
142 | ENDTRYif(!(except_state&1) && exc != 0) except_rethrow( exc); except_free(except_ch.except_obj.except_dyndata); except_pop (); };};
6 | ← | Taking false branch | →
143 |
144 | if (ok) {
7 | ← | Assuming 'ok' is true | →
8 | ← | Taking true branch | →
145 | /*
146 | * Cannot pass a tvb free callback that frees the wmem
147 | * pool, so we make an extra copy that uses bare
148 | * pointers. This could be optimized if tvb API had a
149 | * free pool callback of some sort.
150 | */
151 | unsigned size = wmem_array_get_count(obuf);
152 | uint8_t *p = (uint8_t *)g_malloc(size);
9 | ← | Memory is allocated | →
153 | memcpy(p, wmem_array_get_raw(obuf), size);
154 | out = tvb_new_real_data(p, size, size);
10 | ← | Potential leak of memory pointed to by 'p'
155 | tvb_set_free_cb(out, g_free);
156 | } else {
157 | out = NULL((void*)0);
158 | }
159 |
160 | wmem_destroy_allocator(pool);
161 |
162 | return out;
163 | }
164 |
165 | tvbuff_t *
166 | tvb_child_uncompress_lznt1(tvbuff_t *parent, tvbuff_t *tvb, const unsigned offset, unsigned in_size)
167 | {
168 | tvbuff_t *new_tvb = tvb_uncompress_lznt1(tvb, offset, in_size);
1 | Calling 'tvb_uncompress_lznt1' | →
169 | if (new_tvb)
170 | tvb_set_child_real_data_tvbuff(parent, new_tvb);
171 | return new_tvb;
172 | }
173 |
174 | /*
175 | * Editor modelines - https://www.wireshark.org/tools/modelines.html
176 | *
177 | * Local variables:
178 | * c-basic-offset: 8
179 | * tab-width: 8
180 | * indent-tabs-mode: t
181 | * End:
182 | *
183 | * vi: set shiftwidth=8 tabstop=8 noexpandtab:
184 | * :indentSize=8:tabSize=8:noTabs=false:
185 | */