netfilter: x_tables: fix compat match/target pad out-of-bound write

commit b29c457a6511435960115c0f548c4360d5f4801d upstream.

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>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index e02b8626519424d5cac93a5dda41f31145427ade..5cb5a2957cb27ec7b8768e30bb64fbc42fa83a2e 100644 (file)
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -1209,6 +1209,8 @@ static int translate_compat_table(struct net *net,
        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 4822459e8f425b4139cb09dcbbcb2b8248602d21..9bee964c6a4be556ae34f61a4bbf996ee8478c01 100644 (file)
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -1451,6 +1451,8 @@ translate_compat_table(struct net *net,
        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 21cad30e4546b0fcd5411da4cafb11978def850a..579fda1bc45df3ac96d40339211d77fc0cedb929 100644 (file)
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -1476,6 +1476,8 @@ translate_compat_table(struct net *net,
        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 cef5674ea434c184008b5c6b2b852d09ae413610..059f9fa0f6c91d701431a23d6c1b2b3d4599b2c2 100644 (file)
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -569,7 +569,7 @@ void xt_compat_match_from_user(struct xt_entry_match *m, void **dstptr,
 {
        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)];
 
@@ -579,9 +579,6 @@ void xt_compat_match_from_user(struct xt_entry_match *m, void **dstptr,
                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;
@@ -927,7 +924,7 @@ void xt_compat_target_from_user(struct xt_entry_target *t, void **dstptr,
 {
        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)];
 
@@ -937,9 +934,6 @@ void xt_compat_target_from_user(struct xt_entry_target *t, void **dstptr,
                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;