diff options
| author | Phil Sutter <phil@nwl.cc> | 2024-01-31 18:08:43 +0100 |
|---|---|---|
| committer | Phil Sutter <phil@nwl.cc> | 2024-02-01 14:51:30 +0100 |
| commit | 933e605154c439218f73f48b028abbeed336c3c5 (patch) | |
| tree | 1f48566e6378af5fbd3c11c2d2a40f51c1ea9680 /iptables/xshared.c | |
| parent | 3a135363c9e73dd51535c58b65afd4be65a4be64 (diff) | |
xshared: Fix for memleak in option merging with ebtables
The crucial difference in ebtables is that all extensions are loaded up
front instead of while parsing -m/-j flags. Since this loading of all
extensions before every call to do_parse() is pointless overhead (cf.
ebtables-restore), other tools' mechanism of freeing all merged options
in xtables_free_opts() after handling each command and resetting
xt_params->opts at the start of the parser loop is problematic.
Fixed commit entailed a hack to defeat the xt_params->opts happening at
start of do_parse() by assigning to xt_params->orig_opts after loading
all extensions. This approach caused a memleak though since
xtables_free_opts() called from xtables_merge_options() will free the
opts pointer only if it differs from orig_opts.
Resolve this via a different approach which eliminates the
xt_params->opts reset at the start of do_parse():
Make xt_params->opts be NULL until the first extension is loaded. Option
merging in command_match() and command_jump() tolerates a NULL pointer
there after minimal adjustment. Deinit in xtables_free_opts() is already
fine as it (re)turns xt_params->opts to a NULL pointer. With do_parse()
expecting that and falling back to xt_params->orig_opts, no explicit
initialization is required anymore and thus ebtables' init is not
mangled by accident.
A critical part is that do_parse() checks xt_params->opts pointer upon
each call to getopt_long() as it may get assigned while parsing.
Fixes: 58d364c7120b5 ("ebtables: Use do_parse() from xshared")
Signed-off-by: Phil Sutter <phil@nwl.cc>
Diffstat (limited to 'iptables/xshared.c')
| -rw-r--r-- | iptables/xshared.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/iptables/xshared.c b/iptables/xshared.c index 43fa929d..7d073891 100644 --- a/iptables/xshared.c +++ b/iptables/xshared.c @@ -798,6 +798,9 @@ static void command_match(struct iptables_command_state *cs, bool invert) else if (m->extra_opts != NULL) opts = xtables_merge_options(xt_params->orig_opts, opts, m->extra_opts, &m->option_offset); + else + return; + if (opts == NULL) xtables_error(OTHER_PROBLEM, "can't alloc memory!"); xt_params->opts = opts; @@ -856,10 +859,13 @@ void command_jump(struct iptables_command_state *cs, const char *jumpto) opts = xtables_options_xfrm(xt_params->orig_opts, opts, cs->target->x6_options, &cs->target->option_offset); - else + else if (cs->target->extra_opts != NULL) opts = xtables_merge_options(xt_params->orig_opts, opts, cs->target->extra_opts, &cs->target->option_offset); + else + return; + if (opts == NULL) xtables_error(OTHER_PROBLEM, "can't alloc memory!"); xt_params->opts = opts; @@ -1484,10 +1490,10 @@ void do_parse(int argc, char *argv[], demand-load a protocol. */ opterr = 0; - xt_params->opts = xt_params->orig_opts; while ((cs->c = getopt_long(argc, argv, optstring_lookup(afinfo->family), - xt_params->opts, NULL)) != -1) { + xt_params->opts ?: xt_params->orig_opts, + NULL)) != -1) { switch (cs->c) { /* * Command selection |