[PATCH] xfrm/compat: Fix general protection fault in xfrm_user_rcv_msg_compat()

[YueHaibing]

In xfrm_user_rcv_msg_compat() if maxtype is not zero and less than
XFRMA_MAX, nlmsg_parse_deprecated() do not initialize attrs array fully.
xfrm_xlate32() will access uninit 'attrs[i]' while iterating all attrs
array.

KASAN: probably user-memory-access in range [0x0000000041b58ab0-0x0000000041b58ab7]
CPU: 0 PID: 15799 Comm: syz-executor.2 Tainted: G        W         5.14.0-rc1-syzkaller #0
RIP: 0010:nla_type include/net/netlink.h:1130 [inline]
RIP: 0010:xfrm_xlate32_attr net/xfrm/xfrm_compat.c:410 [inline]
RIP: 0010:xfrm_xlate32 net/xfrm/xfrm_compat.c:532 [inline]
RIP: 0010:xfrm_user_rcv_msg_compat+0x5e5/0x1070 net/xfrm/xfrm_compat.c:577
[...]
Call Trace:
 xfrm_user_rcv_msg+0x556/0x8b0 net/xfrm/xfrm_user.c:2774
 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504
 xfrm_netlink_rcv+0x6b/0x90 net/xfrm/xfrm_user.c:2824
 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340
 netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929
 sock_sendmsg_nosec net/socket.c:702 [inline]

Fixes: 5106f4a8acff ("xfrm/compat: Add 32=>64-bit messages translator")
Signed-off-by: YueHaibing <yuehaibing@xxxxxxxxxx>
---
 net/xfrm/xfrm_compat.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/xfrm/xfrm_compat.c b/net/xfrm/xfrm_compat.c
index a20aec9d7393..4738660cadea 100644
--- a/net/xfrm/xfrm_compat.c
+++ b/net/xfrm/xfrm_compat.c
@@ -559,8 +559,8 @@ static struct nlmsghdr *xfrm_user_rcv_msg_compat(const struct nlmsghdr *h32,
 	    (h32->nlmsg_flags & NLM_F_DUMP))
 		return NULL;
 
-	err = nlmsg_parse_deprecated(h32, compat_msg_min[type], attrs,
-			maxtype ? : XFRMA_MAX, policy ? : compat_policy, extack);
+	err = nlmsg_parse_deprecated(h32, compat_msg_min[type], attrs, XFRMA_MAX,
+				     policy ? : compat_policy, extack);
 	if (err < 0)
 		return ERR_PTR(err);
 
-- 
2.20.1