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authorEric Dumazet <edumazet@google.com>2017-10-05 02:50:07 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-09-19 22:48:59 +0200
commitf9845426f4427eb0031b562dfd5c0ffe99cba644 (patch)
treeb9781aac456ff593f24f18a01135aaa086a8c5cd
parenta3b92ee6fc171d7c9d9b6b829b7fef169210440c (diff)
netfilter: x_tables: avoid stack-out-of-bounds read in xt_copy_counters_from_user
commit e466af75c074e76107ae1cd5a2823e9c61894ffb upstream. syzkaller reports an out of bound read in strlcpy(), triggered by xt_copy_counters_from_user() Fix this by using memcpy(), then forcing a zero byte at the last position of the destination, as Florian did for the non COMPAT code. Fixes: d7591f0c41ce ("netfilter: x_tables: introduce and use xt_copy_counters_from_user") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Willem de Bruijn <willemb@google.com> Acked-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Cc: Greg Hackmann <ghackmann@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--net/netfilter/x_tables.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index 1f3c305df45d..b6e72af15237 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -876,7 +876,7 @@ void *xt_copy_counters_from_user(const void __user *user, unsigned int len,
if (copy_from_user(&compat_tmp, user, sizeof(compat_tmp)) != 0)
return ERR_PTR(-EFAULT);
- strlcpy(info->name, compat_tmp.name, sizeof(info->name));
+ memcpy(info->name, compat_tmp.name, sizeof(info->name) - 1);
info->num_counters = compat_tmp.num_counters;
user += sizeof(compat_tmp);
} else
@@ -889,9 +889,9 @@ void *xt_copy_counters_from_user(const void __user *user, unsigned int len,
if (copy_from_user(info, user, sizeof(*info)) != 0)
return ERR_PTR(-EFAULT);
- info->name[sizeof(info->name) - 1] = '\0';
user += sizeof(*info);
}
+ info->name[sizeof(info->name) - 1] = '\0';
size = sizeof(struct xt_counters);
size *= info->num_counters;