syzbot reports following splat:
BUG: KMSAN: uninit-value in ebt_stp_mt_check+0x24b/0x450
net/bridge/netfilter/ebt_stp.c:162
ebt_stp_mt_check+0x24b/0x450 net/bridge/netfilter/ebt_stp.c:162
xt_check_match+0x1438/0x1650 net/netfilter/x_tables.c:506
ebt_check_match net/bridge/netfilter/ebtables.c:372 [inline]
ebt_check_entry net/bridge/netfilter/ebtables.c:702 [inline]
The uninitialised access is
xt_mtchk_param->nft_compat
... which should be set to 0.
Fix it by zeroing the struct beforehand, same for tgchk.
ip(6)tables targetinfo uses c99-style initialiser, so no change
needed there.
Reported-by: syzbot+da4494182233c23a5fcf@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 55917a21d0cc0 ("netfilter: x_tables: add context to know if extension runs from nft_compat")
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
---
net/bridge/netfilter/ebtables.c | 2 ++
net/ipv4/netfilter/ip_tables.c | 1 +
net/ipv6/netfilter/ip6_tables.c | 1 +
3 files changed, 4 insertions(+)
diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index c2138e7e8263..93600aa606a8 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -709,6 +709,8 @@ ebt_check_entry(struct ebt_entry *e, struct net *net,
}
i = 0;
+ memset(&mtpar, 0, sizeof(mtpar));
+ memset(&tgpar, 0, sizeof(tgpar));
mtpar.net = tgpar.net = net;
mtpar.table = tgpar.table = name;
mtpar.entryinfo = tgpar.entryinfo = e;
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 38ab97b0a2ec..ca0dad90803a 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -531,6 +531,7 @@ find_check_entry(struct ipt_entry *e, struct net *net, const char *name,
return -ENOMEM;
j = 0;
+ memset(&mtpar, 0, sizeof(mtpar));
mtpar.net = net;
mtpar.table = name;
mtpar.entryinfo = &e->ip;
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 0758b5bcfb29..7eab959734bc 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -550,6 +550,7 @@ find_check_entry(struct ip6t_entry *e, struct net *net, const char *name,
return -ENOMEM;
j = 0;
+ memset(&mtpar, 0, sizeof(mtpar));
mtpar.net = net;
mtpar.table = name;
mtpar.entryinfo = &e->ipv6;
--
2.16.4
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