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block-dns using iservice: fix a potential double free

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- An item added to undo-list was not removed on error, causing
  attempt to free again in Undo().
  Also fix a memory leak possibility in the same context.

Github: fixes OpenVPN/openvpn#232

v2: Split add and delete functions and reuse the delete
function for cleanup.

Signed-off-by: Selva Nair <selva.nair@gmail.com>
Acked-by: Lev Stipakov <lstipakov@gmail.com>
Message-Id: <20230201170735.2266851-1-selva.nair@gmail.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg26130.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
This commit is contained in:
Selva Nair 2023-02-01 12:07:35 -05:00 committed by Gert Doering
parent b2e49465e6
commit b761cb9bc9
1 changed files with 78 additions and 54 deletions
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132
src/openvpnserv/interactive.c
View file

@ -777,87 +777,111 @@ CmpAny(LPVOID item, LPVOID any)
}
static DWORD
HandleBlockDNSMessage(const block_dns_message_t *msg, undo_lists_t *lists)
DeleteBlockDNS(const block_dns_message_t *msg, undo_lists_t *lists)
{
DWORD err = 0;
block_dns_data_t *interface_data;
block_dns_data_t *interface_data = RemoveListItem(&(*lists)[block_dns], CmpAny, NULL);
if (interface_data)
{
err = delete_block_dns_filters(interface_data->engine);
if (interface_data->metric_v4 >= 0)
{
set_interface_metric(msg->iface.index, AF_INET,
interface_data->metric_v4);
}
if (interface_data->metric_v6 >= 0)
{
set_interface_metric(msg->iface.index, AF_INET6,
interface_data->metric_v6);
}
free(interface_data);
}
else
{
MsgToEventLog(M_ERR, TEXT("No previous block DNS filters to delete"));
}
return err;
}
static DWORD
AddBlockDNS(const block_dns_message_t *msg, undo_lists_t *lists)
{
DWORD err = 0;
block_dns_data_t *interface_data = NULL;
HANDLE engine = NULL;
LPCWSTR exe_path;
exe_path = settings.exe_path;
if (msg->header.type == msg_add_block_dns)
err = add_block_dns_filters(&engine, msg->iface.index, exe_path, BlockDNSErrHandler);
if (!err)
{
err = add_block_dns_filters(&engine, msg->iface.index, exe_path, BlockDNSErrHandler);
interface_data = malloc(sizeof(block_dns_data_t));
if (!interface_data)
{
err = ERROR_OUTOFMEMORY;
goto out;
}
interface_data->engine = engine;
interface_data->index = msg->iface.index;
int is_auto = 0;
interface_data->metric_v4 = get_interface_metric(msg->iface.index,
AF_INET, &is_auto);
if (is_auto)
{
interface_data->metric_v4 = 0;
}
interface_data->metric_v6 = get_interface_metric(msg->iface.index,
AF_INET6, &is_auto);
if (is_auto)
{
interface_data->metric_v6 = 0;
}
err = AddListItem(&(*lists)[block_dns], interface_data);
if (!err)
{
interface_data = malloc(sizeof(block_dns_data_t));
if (!interface_data)
{
return ERROR_OUTOFMEMORY;
}
interface_data->engine = engine;
interface_data->index = msg->iface.index;
int is_auto = 0;
interface_data->metric_v4 = get_interface_metric(msg->iface.index,
AF_INET, &is_auto);
if (is_auto)
{
interface_data->metric_v4 = 0;
}
interface_data->metric_v6 = get_interface_metric(msg->iface.index,
AF_INET6, &is_auto);
if (is_auto)
{
interface_data->metric_v6 = 0;
}
err = AddListItem(&(*lists)[block_dns], interface_data);
err = set_interface_metric(msg->iface.index, AF_INET,
BLOCK_DNS_IFACE_METRIC);
if (!err)
{
err = set_interface_metric(msg->iface.index, AF_INET,
err = set_interface_metric(msg->iface.index, AF_INET6,
BLOCK_DNS_IFACE_METRIC);
if (!err)
{
set_interface_metric(msg->iface.index, AF_INET6,
BLOCK_DNS_IFACE_METRIC);
}
}
}
}
else
{
interface_data = RemoveListItem(&(*lists)[block_dns], CmpAny, NULL);
if (interface_data)
{
engine = interface_data->engine;
err = delete_block_dns_filters(engine);
engine = NULL;
if (interface_data->metric_v4 >= 0)
if (err)
{
set_interface_metric(msg->iface.index, AF_INET,
interface_data->metric_v4);
/* delete the filters, remove undo item and free interface data */
DeleteBlockDNS(msg, lists);
engine = NULL;
}
if (interface_data->metric_v6 >= 0)
{
set_interface_metric(msg->iface.index, AF_INET6,
interface_data->metric_v6);
}
free(interface_data);
}
else
{
MsgToEventLog(M_ERR, TEXT("No previous block DNS filters to delete"));
}
}
out:
if (err && engine)
{
delete_block_dns_filters(engine);
free(interface_data);
}
return err;
}
static DWORD
HandleBlockDNSMessage(const block_dns_message_t *msg, undo_lists_t *lists)
{
if (msg->header.type == msg_add_block_dns)
{
return AddBlockDNS(msg, lists);
}
else
{
return DeleteBlockDNS(msg, lists);
}
}
/*
* Execute a command and return its exit code. If timeout > 0, terminate
* the process if still running after timeout milliseconds. In that case