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280 lines
11 KiB
280 lines
11 KiB
From 26de3af817b0c5746cb61b798ae8e138e01ea17c Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
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Date: Mon, 9 Jul 2018 07:03:01 +0200
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Subject: [PATCH] Introduce free_and_strndup and use it in bus-message.c
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v2: fix error in free_and_strndup()
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When the orignal and copied message were the same, but shorter than specified
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length l, memory read past the end of the buffer would be performed. A test
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case is included: a string that had an embedded NUL ("q\0") is used to replace
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"q".
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v3: Fix one more bug in free_and_strndup and add tests.
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v4: Some style fixed based on review, one more use of free_and_replace, and
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make the tests more comprehensive.
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(cherry picked from commit 7f546026abbdc56c453a577e52d57159458c3e9c)
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Resolves: #1635428
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---
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src/basic/string-util.c | 28 +++++++-
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src/basic/string-util.h | 1 +
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src/libsystemd/sd-bus/bus-message.c | 34 ++++------
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src/test/test-string-util.c | 62 ++++++++++++++++++
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...h-b88ad9ecf4aacf4a0caca5b5543953265367f084 | Bin 0 -> 32 bytes
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5 files changed, 103 insertions(+), 22 deletions(-)
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create mode 100644 test/fuzz/fuzz-bus-message/crash-b88ad9ecf4aacf4a0caca5b5543953265367f084
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diff --git a/src/basic/string-util.c b/src/basic/string-util.c
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index 0a40683493..dfa739996f 100644
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--- a/src/basic/string-util.c
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+++ b/src/basic/string-util.c
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@@ -1004,7 +1004,7 @@ int free_and_strdup(char **p, const char *s) {
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assert(p);
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- /* Replaces a string pointer with an strdup()ed new string,
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+ /* Replaces a string pointer with a strdup()ed new string,
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* possibly freeing the old one. */
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if (streq_ptr(*p, s))
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@@ -1023,6 +1023,32 @@ int free_and_strdup(char **p, const char *s) {
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return 1;
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}
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+int free_and_strndup(char **p, const char *s, size_t l) {
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+ char *t;
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+
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+ assert(p);
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+ assert(s || l == 0);
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+
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+ /* Replaces a string pointer with a strndup()ed new string,
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+ * freeing the old one. */
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+
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+ if (!*p && !s)
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+ return 0;
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+
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+ if (*p && s && strneq(*p, s, l) && (l > strlen(*p) || (*p)[l] == '\0'))
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+ return 0;
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+
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+ if (s) {
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+ t = strndup(s, l);
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+ if (!t)
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+ return -ENOMEM;
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+ } else
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+ t = NULL;
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+
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+ free_and_replace(*p, t);
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+ return 1;
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+}
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+
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#if !HAVE_EXPLICIT_BZERO
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/*
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* Pointer to memset is volatile so that compiler must de-reference
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diff --git a/src/basic/string-util.h b/src/basic/string-util.h
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index c0cc4e78d7..96a9260f93 100644
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--- a/src/basic/string-util.h
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+++ b/src/basic/string-util.h
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@@ -176,6 +176,7 @@ char *strrep(const char *s, unsigned n);
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int split_pair(const char *s, const char *sep, char **l, char **r);
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int free_and_strdup(char **p, const char *s);
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+int free_and_strndup(char **p, const char *s, size_t l);
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/* Normal memmem() requires haystack to be nonnull, which is annoying for zero-length buffers */
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static inline void *memmem_safe(const void *haystack, size_t haystacklen, const void *needle, size_t needlelen) {
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diff --git a/src/libsystemd/sd-bus/bus-message.c b/src/libsystemd/sd-bus/bus-message.c
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index 381034f5f8..7c8bad2bdd 100644
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--- a/src/libsystemd/sd-bus/bus-message.c
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+++ b/src/libsystemd/sd-bus/bus-message.c
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@@ -4175,20 +4175,19 @@ _public_ int sd_bus_message_peek_type(sd_bus_message *m, char *type, const char
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if (contents) {
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size_t l;
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- char *sig;
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r = signature_element_length(c->signature+c->index+1, &l);
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if (r < 0)
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return r;
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- assert(l >= 1);
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+ /* signature_element_length does verification internally */
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- sig = strndup(c->signature + c->index + 1, l);
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- if (!sig)
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+ assert(l >= 1);
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+ if (free_and_strndup(&c->peeked_signature,
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+ c->signature + c->index + 1, l) < 0)
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return -ENOMEM;
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- free(c->peeked_signature);
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- *contents = c->peeked_signature = sig;
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+ *contents = c->peeked_signature;
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}
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if (type)
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@@ -4201,19 +4200,17 @@ _public_ int sd_bus_message_peek_type(sd_bus_message *m, char *type, const char
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if (contents) {
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size_t l;
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- char *sig;
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r = signature_element_length(c->signature+c->index, &l);
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if (r < 0)
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return r;
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assert(l >= 2);
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- sig = strndup(c->signature + c->index + 1, l - 2);
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- if (!sig)
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+ if (free_and_strndup(&c->peeked_signature,
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+ c->signature + c->index + 1, l - 2) < 0)
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return -ENOMEM;
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- free(c->peeked_signature);
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- *contents = c->peeked_signature = sig;
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+ *contents = c->peeked_signature;
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}
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if (type)
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@@ -4253,9 +4250,8 @@ _public_ int sd_bus_message_peek_type(sd_bus_message *m, char *type, const char
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if (k > c->item_size)
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return -EBADMSG;
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- free(c->peeked_signature);
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- c->peeked_signature = strndup((char*) q + 1, k - 1);
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- if (!c->peeked_signature)
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+ if (free_and_strndup(&c->peeked_signature,
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+ (char*) q + 1, k - 1) < 0)
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return -ENOMEM;
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if (!signature_is_valid(c->peeked_signature, true))
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@@ -5085,25 +5081,21 @@ int bus_message_parse_fields(sd_bus_message *m) {
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if (*p == 0) {
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size_t l;
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- char *c;
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/* We found the beginning of the signature
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* string, yay! We require the body to be a
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* structure, so verify it and then strip the
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* opening/closing brackets. */
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- l = ((char*) m->footer + m->footer_accessible) - p - (1 + sz);
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+ l = (char*) m->footer + m->footer_accessible - p - (1 + sz);
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if (l < 2 ||
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p[1] != SD_BUS_TYPE_STRUCT_BEGIN ||
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p[1 + l - 1] != SD_BUS_TYPE_STRUCT_END)
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return -EBADMSG;
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- c = strndup(p + 1 + 1, l - 2);
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- if (!c)
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+ if (free_and_strndup(&m->root_container.signature,
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+ p + 1 + 1, l - 2) < 0)
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return -ENOMEM;
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-
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- free(m->root_container.signature);
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- m->root_container.signature = c;
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break;
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}
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diff --git a/src/test/test-string-util.c b/src/test/test-string-util.c
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index 3e72ce2c0a..43a6b14c34 100644
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--- a/src/test/test-string-util.c
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+++ b/src/test/test-string-util.c
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@@ -5,6 +5,7 @@
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#include "macro.h"
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#include "string-util.h"
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#include "strv.h"
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+#include "tests.h"
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#include "utf8.h"
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static void test_string_erase(void) {
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@@ -30,6 +31,64 @@ static void test_string_erase(void) {
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assert_se(x[9] == '\0');
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}
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+static void test_free_and_strndup_one(char **t, const char *src, size_t l, const char *expected, bool change) {
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+ int r;
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+
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+ log_debug("%s: \"%s\", \"%s\", %zd (expect \"%s\", %s)",
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+ __func__, strnull(*t), strnull(src), l, strnull(expected), yes_no(change));
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+
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+ r = free_and_strndup(t, src, l);
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+ assert_se(streq_ptr(*t, expected));
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+ assert_se(r == change); /* check that change occurs only when necessary */
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+}
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+
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+static void test_free_and_strndup(void) {
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+ static const struct test_case {
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+ const char *src;
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+ size_t len;
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+ const char *expected;
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+ } cases[] = {
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+ {"abc", 0, ""},
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+ {"abc", 0, ""},
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+ {"abc", 1, "a"},
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+ {"abc", 2, "ab"},
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+ {"abc", 3, "abc"},
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+ {"abc", 4, "abc"},
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+ {"abc", 5, "abc"},
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+ {"abc", 5, "abc"},
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+ {"abc", 4, "abc"},
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+ {"abc", 3, "abc"},
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+ {"abc", 2, "ab"},
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+ {"abc", 1, "a"},
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+ {"abc", 0, ""},
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+
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+ {"", 0, ""},
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+ {"", 1, ""},
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+ {"", 2, ""},
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+ {"", 0, ""},
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+ {"", 1, ""},
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+ {"", 2, ""},
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+ {"", 2, ""},
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+ {"", 1, ""},
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+ {"", 0, ""},
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+
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+ {NULL, 0, NULL},
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+
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+ {"foo", 3, "foo"},
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+ {"foobar", 6, "foobar"},
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+ };
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+
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+ _cleanup_free_ char *t = NULL;
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+ const char *prev_expected = t;
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+
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+ for (unsigned i = 0; i < ELEMENTSOF(cases); i++) {
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+ test_free_and_strndup_one(&t,
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+ cases[i].src, cases[i].len, cases[i].expected,
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+ !streq_ptr(cases[i].expected, prev_expected));
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+ prev_expected = t;
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+ }
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+}
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+
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static void test_ascii_strcasecmp_n(void) {
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assert_se(ascii_strcasecmp_n("", "", 0) == 0);
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@@ -497,7 +556,10 @@ static void test_memory_startswith(void) {
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}
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int main(int argc, char *argv[]) {
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+ test_setup_logging(LOG_DEBUG);
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+
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test_string_erase();
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+ test_free_and_strndup();
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test_ascii_strcasecmp_n();
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test_ascii_strcasecmp_nn();
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test_cellescape();
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diff --git a/test/fuzz/fuzz-bus-message/crash-b88ad9ecf4aacf4a0caca5b5543953265367f084 b/test/fuzz/fuzz-bus-message/crash-b88ad9ecf4aacf4a0caca5b5543953265367f084
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new file mode 100644
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index 0000000000000000000000000000000000000000..52469650b5498a45d5d95bd9d933c989cfb47ca7
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GIT binary patch
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literal 32
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ccmd1#|DTBg0(2Mzp)7_%AVVXuuuM|`09r!?!~g&Q
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literal 0
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HcmV?d00001
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