net: fix NULL pointer reference in cipso_v4_doi_free

In netlbl_cipsov4_add_std() when 'doi_def->map.std' alloc
failed, we sometime observe panic:

  BUG: kernel NULL pointer dereference, address:
  ...
  RIP: 0010:cipso_v4_doi_free+0x3a/0x80
  ...
  Call Trace:
   netlbl_cipsov4_add_std+0xf4/0x8c0
   netlbl_cipsov4_add+0x13f/0x1b0
   genl_family_rcv_msg_doit.isra.15+0x132/0x170
   genl_rcv_msg+0x125/0x240

This is because in cipso_v4_doi_free() there is no check
on 'doi_def->map.std' when doi_def->type got value 1, which
is possibe, since netlbl_cipsov4_add_std() haven't initialize
it before alloc 'doi_def->map.std'.

This patch just add the check to prevent panic happen in similar
cases.

Reported-by: Abaci <abaci@linux.alibaba.com>
Signed-off-by: Michael Wang <yun.wang@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/netlabel/netlabel_cipso_v4.c b/net/netlabel/netlabel_cipso_v4.c
index 000bb3d..894e6b8 100644 (file)
--- a/net/netlabel/netlabel_cipso_v4.c
+++ b/net/netlabel/netlabel_cipso_v4.c
@@ -144,8 +144,8 @@ static int netlbl_cipsov4_add_std(struct genl_info *info,
                return -ENOMEM;
        doi_def->map.std = kzalloc(sizeof(*doi_def->map.std), GFP_KERNEL);
        if (doi_def->map.std == NULL) {
-               ret_val = -ENOMEM;
-               goto add_std_failure;
+               kfree(doi_def);
+               return -ENOMEM;
        }
        doi_def->type = CIPSO_V4_MAP_TRANS;