4.4-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
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
--- net/netfilter/x_tables.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -876,7 +876,7 @@ void *xt_copy_counters_from_user(const v 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 v 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;