diff options
| author | Florent Revest <revest@chromium.org> | 2023-07-03 16:52:16 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-08-11 11:45:17 +0200 |
| commit | 00716f25f9697d02a0d9bd622575c7c7321ba3d0 (patch) | |
| tree | 800c957ae3cc0f6107613ed20e68bafdf18576d0 | |
| parent | db04f3a0dcc83f7014836be64a1fbf04a50bcc3c (diff) | |
netfilter: conntrack: Avoid nf_ct_helper_hash uses after free
commit 6eef7a2b933885a17679eb8ed0796ddf0ee5309b upstream.
If nf_conntrack_init_start() fails (for example due to a
register_nf_conntrack_bpf() failure), the nf_conntrack_helper_fini()
clean-up path frees the nf_ct_helper_hash map.
When built with NF_CONNTRACK=y, further netfilter modules (e.g:
netfilter_conntrack_ftp) can still be loaded and call
nf_conntrack_helpers_register(), independently of whether nf_conntrack
initialized correctly. This accesses the nf_ct_helper_hash dangling
pointer and causes a uaf, possibly leading to random memory corruption.
This patch guards nf_conntrack_helper_register() from accessing a freed
or uninitialized nf_ct_helper_hash pointer and fixes possible
uses-after-free when loading a conntrack module.
Cc: stable@vger.kernel.org
Fixes: 12f7a505331e ("netfilter: add user-space connection tracking helper infrastructure")
Signed-off-by: Florent Revest <revest@chromium.org>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | net/netfilter/nf_conntrack_helper.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c index e24b762ffa1d..06c70d4584cf 100644 --- a/net/netfilter/nf_conntrack_helper.c +++ b/net/netfilter/nf_conntrack_helper.c @@ -400,6 +400,9 @@ int nf_conntrack_helper_register(struct nf_conntrack_helper *me) BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES); BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1); + if (!nf_ct_helper_hash) + return -ENOENT; + if (me->expect_policy->max_expected > NF_CT_EXPECT_MAX_CNT) return -EINVAL; @@ -570,4 +573,5 @@ void nf_conntrack_helper_fini(void) { nf_ct_extend_unregister(&helper_extend); kvfree(nf_ct_helper_hash); + nf_ct_helper_hash = NULL; } |