8000 mem leak due to `ares__hosts_entry_to_hostent()` allocation strategy by bradh352 · Pull Request #824 · c-ares/c-ares · GitHub
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me 8000 m leak due to ares__hosts_entry_to_hostent() allocation strategy #824

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Merged
merged 2 commits into from
Jul 22, 2024
Merged

mem leak due to ares__hosts_entry_to_hostent() allocation strategy #824

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1c562c1
ares__hosts_entry_to_hostent() uses different allocation concepts for…
bradh352 Jul 22, 2024
7877e64
fix leak
bradh352 Jul 22, 2024
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162 changes: 38 additions & 124 deletions src/lib/ares__hosts_file.c
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Original file line number Diff line number Diff line change
Expand Up @@ -767,126 +767,6 @@ ares_status_t ares__hosts_search_host(ares_channel_t *channel,
return ARES_SUCCESS;
}

ares_status_t ares__hosts_entry_to_hostent(const ares_hosts_entry_t *entry,
int family, struct hostent **hostent)
{
ares_status_t status;
size_t naliases;
ares__llist_node_t *node;
size_t idx;

*hostent = ares_malloc_zero(sizeof(**hostent));
if (*hostent == NULL) {
status = ARES_ENOMEM; /* LCOV_EXCL_LINE: OutOfMemory */
goto fail; /* LCOV_EXCL_LINE: OutOfMemory */
}

(*hostent)->h_addrtype = (HOSTENT_ADDRTYPE_TYPE)family;

/* Copy IP addresses that match the address family */
idx = 0;
for (node = ares__llist_node_first(entry->ips); node != NULL;
node = ares__llist_node_next(node)) {
struct ares_addr addr;
const void *ptr = NULL;
size_t ptr_len = 0;
const char *ipaddr = ares__llist_node_val(node);
char **temp = NULL;

memset(&addr, 0, sizeof(addr));

addr.family = family;
ptr = ares_dns_pton(ipaddr, &addr, &ptr_len);
if (ptr == NULL) {
continue;
}

/* If family == AF_UNSPEC, then we want to inherit this for future
* conversions as we can only support a single address class */
if (family == AF_UNSPEC) {
family = addr.family;
(*hostent)->h_addrtype = (HOSTENT_ADDRTYPE_TYPE)addr.family;
}

temp = ares_realloc_zero((*hostent)->h_addr_list,
(idx + 1) * sizeof(*(*hostent)->h_addr_list),
(idx + 2) * sizeof(*(*hostent)->h_addr_list));
if (temp == NULL) {
status = ARES_ENOMEM; /* LCOV_EXCL_LINE: OutOfMemory */
goto fail; /* LCOV_EXCL_LINE: OutOfMemory */
}

(*hostent)->h_addr_list = temp;

(*hostent)->h_addr_list[idx] = ares_malloc(ptr_len);
if ((*hostent)->h_addr_list[idx] == NULL) {
status = ARES_ENOMEM; /* LCOV_EXCL_LINE: OutOfMemory */
goto fail; /* LCOV_EXCL_LINE: OutOfMemory */
}

memcpy((*hostent)->h_addr_list[idx], ptr, ptr_len);
idx++;
(*hostent)->h_length = (HOSTENT_LENGTH_TYPE)ptr_len;
}

/* entry didn't match address class */
if (idx == 0) {
status = ARES_ENOTFOUND;
goto fail;
}

/* Copy main hostname */
(*hostent)->h_name = ares_strdup(ares__llist_first_val(entry->hosts));
if ((*hostent)->h_name == NULL) {
status = ARES_ENOMEM; /* LCOV_EXCL_LINE: OutOfMemory */
goto fail; /* LCOV_EXCL_LINE: OutOfMemory */
}

/* Copy aliases */
naliases = ares__llist_len(entry->hosts) - 1;

/* Cap at 100, some people use https://github.com/StevenBlack/hosts and we
* don't need 200k+ aliases */
if (naliases > 100) {
naliases = 100; /* LCOV_EXCL_LINE: DefensiveCoding */
}

(*hostent)->h_aliases =
ares_malloc_zero((naliases + 1) * sizeof(*(*hostent)->h_aliases));
if ((*hostent)->h_aliases == NULL) {
status = ARES_ENOMEM; /* LCOV_EXCL_LINE: OutOfMemory */
goto fail; /* LCOV_EXCL_LINE: OutOfMemory */
}

/* Copy all entries to the alias except the first */
idx = 0;
node = ares__llist_node_first(entry->hosts);
node = ares__llist_node_next(node);
while (node != NULL) {
(*hostent)->h_aliases[idx] = ares_strdup(ares__llist_node_val(node));
if ((*hostent)->h_aliases[idx] == NULL) {
status = ARES_ENOMEM; /* LCOV_EXCL_LINE: OutOfMemory */
goto fail; /* LCOV_EXCL_LINE: OutOfMemory */
}
idx++;

/* Break out if artificially capped */
if (idx == naliases) {
break;
}
node = ares__llist_node_next(node);
}

return ARES_SUCCESS;

/* LCOV_EXCL_START: defensive coding */
fail:
ares_free_hostent(*hostent);
*hostent = NULL;
return status;
/* LCOV_EXCL_STOP */
}

static ares_status_t
ares__hosts_ai_append_cnames(const ares_hosts_entry_t *entry,
struct ares_addrinfo_cname **cnames_out)
Expand Down Expand Up @@ -980,10 +860,12 @@ ares_status_t ares__hosts_entry_to_addrinfo(const ares_hosts_entry_t *entry,
return ARES_EBADFAMILY; /* LCOV_EXCL_LINE: DefensiveCoding */
}

ai->name = ares_strdup(name);
if (ai->name == NULL) {
status = ARES_ENOMEM; /* LCOV_EXCL_LINE: OutOfMemory */
goto done; /* LCOV_EXCL_LINE: OutOfMemory */
if (name != NULL) {
ai->name = ares_strdup(name);
if (ai->name == NULL) {
status = ARES_ENOMEM; /* LCOV_EXCL_LINE: OutOfMemory */
goto done; /* LCOV_EXCL_LINE: OutOfMemory */
}
}

for (node = ares__llist_node_first(entry->ips); node != NULL;
Expand Down Expand Up @@ -1031,3 +913,35 @@ ares_status_t ares__hosts_entry_to_addrinfo(const ares_hosts_entry_t *entry,

return status;
}

ares_status_t ares__hosts_entry_to_hostent(const ares_hosts_entry_t *entry,
int family, struct hostent **hostent)
{
ares_status_t status;
struct ares_addrinfo *ai = ares_malloc_zero(sizeof(*ai));

*hostent = NULL;

if (ai == NULL) {
return ARES_ENOMEM;
}

status = ares__hosts_entry_to_addrinfo(entry, NULL, family, 0, ARES_TRUE, ai);
if (status != ARES_SUCCESS) {
goto done;
}

status = ares__addrinfo2hostent(ai, family, hostent);
if (status != ARES_SUCCESS) {
goto done;
}

done:
ares_freeaddrinfo(ai);
if (status != ARES_SUCCESS) {
ares_free_hostent(*hostent);
*hostent = NULL;
}

return status;
}
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