nft: fix out of bound memory copy
Valgrind reports an invalid read after a memory block:
==11114== Invalid read of size 8
==11114== at 0x4C2DB02: memcpy@@GLIBC_2.14 (mc_replace_strmem.c:877)
==11114== by 0x41788E: add_match (nft.c:781)
==11114== by 0x41B54C: nft_ipv4_add (nft-ipv4.c:72)
==11114== by 0x415DF2: nft_rule_new.isra.2 (nft.c:945)
==11114== by 0x418ACE: nft_rule_append (nft.c:1000)
==11114== by 0x413A92: add_entry.isra.6 (xtables.c:424)
==11114== by 0x4152DE: do_commandx (xtables.c:1184)
==11114== by 0x4134E8: xtables_main (xtables-standalone.c:72)
==11114== by 0x5B87994: (below main) (libc-start.c:260)
==11114== Address 0x61399e8 is 8 bytes after a block of size 48 alloc'd
==11114== at 0x4C2B514: calloc (vg_replace_malloc.c:593)
==11114== by 0x52448C8: xtables_calloc (xtables.c:272)
==11114== by 0x410AC2: command_default (xshared.c:150)
==11114== by 0x4149A2: do_commandx (xtables.c:1075)
==11114== by 0x4134E8: xtables_main (xtables-standalone.c:72)
==11114== by 0x5B87994: (below main) (libc-start.c:260)
m->u.match_size also contains the size of the xt_entry_match structure.
Fix also the target path which is very similar.
Reported-by: Ana Rey Botello <anarey@gmail.com>
Tested-by: Ana Rey Botello <anarey@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/iptables/nft.c b/iptables/nft.c
index 01e0264..2135b04 100644
--- a/iptables/nft.c
+++ b/iptables/nft.c
@@ -776,7 +776,7 @@
if (info == NULL)
return -ENOMEM;
- memcpy(info, m->data, m->u.match_size);
+ memcpy(info, m->data, m->u.match_size - sizeof(*m));
nft_rule_expr_set(e, NFT_EXPR_MT_INFO, info, m->u.match_size - sizeof(*m));
return 0;
@@ -799,20 +799,17 @@
static int __add_target(struct nft_rule_expr *e, struct xt_entry_target *t)
{
- void *info = NULL;
+ void *info;
nft_rule_expr_set(e, NFT_EXPR_TG_NAME, t->u.user.name,
strlen(t->u.user.name));
nft_rule_expr_set_u32(e, NFT_EXPR_TG_REV, t->u.user.revision);
- if (info == NULL) {
- info = calloc(1, t->u.target_size);
- if (info == NULL)
- return -ENOMEM;
+ info = calloc(1, t->u.target_size);
+ if (info == NULL)
+ return -ENOMEM;
- memcpy(info, t->data, t->u.target_size);
- }
-
+ memcpy(info, t->data, t->u.target_size - sizeof(*t));
nft_rule_expr_set(e, NFT_EXPR_TG_INFO, info, t->u.target_size - sizeof(*t));
return 0;
