Introduce free_and_strndup and use it in bus-message.c
v2: fix error in free_and_strndup()
When the orignal and copied message were the same, but shorter than specified
length l, memory read past the end of the buffer would be performed. A test
case is included: a string that had an embedded NUL ("q\0") is used to replace
"q".
v3: Fix one more bug in free_and_strndup and add tests.
v4: Some style fixed based on review, one more use of free_and_replace, and
make the tests more comprehensive.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek
parent
56b560c263
commit
7f546026ab
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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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assert(p);
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assert(s || l == 0);
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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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if (!*p && !s)
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return 0;
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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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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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free_and_replace(*p, t);
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return 1;
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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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@ -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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@ -4144,20 +4144,19 @@ _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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@ -4170,19 +4169,17 @@ _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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@ -4222,9 +4219,8 @@ _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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@ -5056,25 +5052,21 @@ 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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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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@ -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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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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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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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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{"", 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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{NULL, 0, NULL},
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{"foo", 3, "foo"},
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{"foobar", 6, "foobar"},
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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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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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static void test_ascii_strcasecmp_n(void) {
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assert_se(ascii_strcasecmp_n("", "", 0) == 0);
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@ -520,7 +579,10 @@ static void test_memory_startswith_no_case(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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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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