### Bug Summary

File: | builds/wireshark/wireshark/epan/tvbuff_lznt1.c
Warning: | line 145, 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-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-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/2026-01-27-100401-3623-1 -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 | for (j = 0; j < match_len; j++) {
66 | uint8_t byte;
67 | if (match_off > out_off)
68 | return false0;
69 | if (wmem_array_try_index(obuf, out_start+out_off-match_off, &byte))
70 | return false0;
71 | wmem_array_append_one(obuf, byte)wmem_array_append((obuf), &(byte), 1);
72 | out_off++;
73 | }
74 | }
75 | if (in_off == in_size) {
76 | goto out;
77 | }
78 | }
79 | }
80 | out:
81 | return true1;
82 | }
83 |
84 | static bool_Bool
85 | do_uncompress(tvbuff_t *tvb, int offset, int in_size, wmem_array_t *obuf)
86 | {
87 | int in_off = 0;
88 | uint32_t header, length, i;
89 | bool_Bool ok;
90 |
91 | if (!tvb)
92 | return false0;
93 |
94 | if (!in_size || in_size > MAX_INPUT_SIZE(16*1024*1024))
95 | return false0;
96 |
97 | while (in_off < in_size) {
98 | header = tvb_get_letohs(tvb, offset+in_off);
99 | in_off += 2;
100 | length = (header & 0x0FFF) + 1;
101 | if (!(header & 0x8000)) {
102 | for (i = 0; i < length; i++) {
103 | uint8_t v = tvb_get_uint8(tvb, offset+in_off);
104 | wmem_array_append_one(obuf, v)wmem_array_append((obuf), &(v), 1);
105 | in_off++;
106 | }
107 | } else {
108 | ok = uncompress_chunk(tvb, offset + in_off, length, obuf);
109 | if (!ok)
110 | return false0;
111 | in_off += length;
112 | }
113 | }
114 | return true1;
115 | }
116 |
117 | tvbuff_t *
118 | tvb_uncompress_lznt1(tvbuff_t *tvb, const unsigned offset, unsigned in_size)
119 | {
120 | volatile bool_Bool ok = false0;
121 | wmem_allocator_t *pool;
122 | wmem_array_t *obuf;
123 | tvbuff_t *out;
124 |
125 | pool = wmem_allocator_new(WMEM_ALLOCATOR_SIMPLE);
126 | obuf = wmem_array_sized_new(pool, 1, in_size*2);
127 |
128 | 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 | →
129 | ok = do_uncompress(tvb, offset, in_size, obuf);
130 | } CATCH_ALLif (except_state == 0 && exc != 0 && (except_state |=1)) {
131 | ok = false0;
132 | }
133 | ENDTRYif(!(except_state&1) && exc != 0) except_rethrow( exc); except_free(except_ch.except_obj.except_dyndata); except_pop (); };};
6 | ← | Taking false branch | →
134 |
135 | if (ok) {
7 | ← | Assuming 'ok' is true | →
8 | ← | Taking true branch | →
136 | /*
137 | * Cannot pass a tvb free callback that frees the wmem
138 | * pool, so we make an extra copy that uses bare
139 | * pointers. This could be optimized if tvb API had a
140 | * free pool callback of some sort.
141 | */
142 | unsigned size = wmem_array_get_count(obuf);
143 | uint8_t *p = (uint8_t *)g_malloc(size);
9 | ← | Memory is allocated | →
144 | memcpy(p, wmem_array_get_raw(obuf), size);
145 | out = tvb_new_real_data(p, size, size);
10 | ← | Potential leak of memory pointed to by 'p'
146 | tvb_set_free_cb(out, g_free);
147 | } else {
148 | out = NULL((void*)0);
149 | }
150 |
151 | wmem_destroy_allocator(pool);
152 |
153 | return out;
154 | }
155 |
156 | tvbuff_t *
157 | tvb_child_uncompress_lznt1(tvbuff_t *parent, tvbuff_t *tvb, const unsigned offset, unsigned in_size)
158 | {
159 | tvbuff_t *new_tvb = tvb_uncompress_lznt1(tvb, offset, in_size);
1 | Calling 'tvb_uncompress_lznt1' | →
160 | if (new_tvb)
161 | tvb_set_child_real_data_tvbuff(parent, new_tvb);
162 | return new_tvb;
163 | }
164 |
165 | /*
166 | * Editor modelines - https://www.wireshark.org/tools/modelines.html
167 | *
168 | * Local variables:
169 | * c-basic-offset: 8
170 | * tab-width: 8
171 | * indent-tabs-mode: t
172 | * End:
173 | *
174 | * vi: set shiftwidth=8 tabstop=8 noexpandtab:
175 | * :indentSize=8:tabSize=8:noTabs=false:
176 | */