[PATCH AUTOSEL 4.14 6/7] net: fix NULL pointer reference in cipso_v4_doi_free

Sasha Levin
2021-08-30T12:02:42Z

From: 王贇 <yun.wang@linux.alibaba.com>

[ Upstream commit 733c99ee8be9a1410287cdbb943887365e83b2d6 ]

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' equal 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 for 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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/ipv4/cipso_ipv4.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index e8b8dd1cb157..7372ba2659df 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -480,14 +480,16 @@ void cipso_v4_doi_free(struct cipso_v4_doi *doi_def)
if (!doi_def)
return;

- switch (doi_def->type) {
- case CIPSO_V4_MAP_TRANS:
- kfree(doi_def->map.std->lvl.cipso);
- kfree(doi_def->map.std->lvl.local);
- kfree(doi_def->map.std->cat.cipso);
- kfree(doi_def->map.std->cat.local);
- kfree(doi_def->map.std);
- break;
+ if (doi_def->map.std) {
+ switch (doi_def->type) {
+ case CIPSO_V4_MAP_TRANS:
+ kfree(doi_def->map.std->lvl.cipso);
+ kfree(doi_def->map.std->lvl.local);
+ kfree(doi_def->map.std->cat.cipso);
+ kfree(doi_def->map.std->cat.local);
+ kfree(doi_def->map.std);
+ break;
+ }
}
kfree(doi_def);
}
--
2.30.2