netfilter: x_tables: fix compat match/target pad out-of-bound write
xt_compat_match/target_from_user doesn't check that zeroing the area
to start of next rule won't write past end of allocated ruleset blob.
Remove this code and zero the entire blob beforehand.
Reported-by: syzbot+cfc0247ac173f597aaaa@syzkaller.appspotmail.com
Reported-by: Andy Nguyen <theflow@google.com>
Fixes: 9fa492cdc160c ("[NETFILTER]: x_tables: simplify compat API")
Signed-off-by: Florian Westphal <fw@strlen.de>
BUG=b/184972382
TEST=Presubmit test
RELEASE_NOTE=Fixd an issue in kernel that netfilter/x_tables.c
may cause out-of-bound write
SOURCE=FROMLIST(https://patchwork.ozlabs.org/project/netfilter-devel/patch/20210407193857.21120-1-fw@strlen.de/)
cos-patch: security-high
Change-Id: I2752c7c9eb17d48790adb6cebd0a7824b2c9f414
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/15632
Main-Branch-Verified: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Roy Yang <royyang@google.com>
(cherry picked from commit 80bec9781ef13e9ae61bb9de5961f701bfd50c99)
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/15791
Reviewed-by: Robert Kolchmeyer <rkolchmeyer@google.com>
Tested-by: Robert Kolchmeyer <rkolchmeyer@google.com>
diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index f1f78a7..dc7dac6 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -1196,6 +1196,8 @@
if (!newinfo)
goto out_unlock;
+ memset(newinfo->entries, 0, size);
+
newinfo->number = compatr->num_entries;
for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
newinfo->hook_entry[i] = compatr->hook_entry[i];
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 10b91eb..0076449 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -1430,6 +1430,8 @@
if (!newinfo)
goto out_unlock;
+ memset(newinfo->entries, 0, size);
+
newinfo->number = compatr->num_entries;
for (i = 0; i < NF_INET_NUMHOOKS; i++) {
newinfo->hook_entry[i] = compatr->hook_entry[i];
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index c973ace..8bb543b 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -1445,6 +1445,8 @@
if (!newinfo)
goto out_unlock;
+ memset(newinfo->entries, 0, size);
+
newinfo->number = compatr->num_entries;
for (i = 0; i < NF_INET_NUMHOOKS; i++) {
newinfo->hook_entry[i] = compatr->hook_entry[i];
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index 5c35d64..9cfee666 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -733,7 +733,7 @@
{
const struct xt_match *match = m->u.kernel.match;
struct compat_xt_entry_match *cm = (struct compat_xt_entry_match *)m;
- int pad, off = xt_compat_match_offset(match);
+ int off = xt_compat_match_offset(match);
u_int16_t msize = cm->u.user.match_size;
char name[sizeof(m->u.user.name)];
@@ -743,9 +743,6 @@
match->compat_from_user(m->data, cm->data);
else
memcpy(m->data, cm->data, msize - sizeof(*cm));
- pad = XT_ALIGN(match->matchsize) - match->matchsize;
- if (pad > 0)
- memset(m->data + match->matchsize, 0, pad);
msize += off;
m->u.user.match_size = msize;
@@ -1116,7 +1113,7 @@
{
const struct xt_target *target = t->u.kernel.target;
struct compat_xt_entry_target *ct = (struct compat_xt_entry_target *)t;
- int pad, off = xt_compat_target_offset(target);
+ int off = xt_compat_target_offset(target);
u_int16_t tsize = ct->u.user.target_size;
char name[sizeof(t->u.user.name)];
@@ -1126,9 +1123,6 @@
target->compat_from_user(t->data, ct->data);
else
memcpy(t->data, ct->data, tsize - sizeof(*ct));
- pad = XT_ALIGN(target->targetsize) - target->targetsize;
- if (pad > 0)
- memset(t->data + target->targetsize, 0, pad);
tsize += off;
t->u.user.target_size = tsize;
