[PATCH 5.11 001/210] xfrm/compat: Cleanup WARN()s that can be user-triggered

Greg Kroah-Hartman
2021-04-12T09:20:50Z

From: Dmitry Safonov <dima@arista.com>

commit ef19e111337f6c3dca7019a8bad5fbc6fb18d635 upstream.

Replace WARN_ONCE() that can be triggered from userspace with
pr_warn_once(). Those still give user a hint what's the issue.

I've left WARN()s that are not possible to trigger with current
code-base and that would mean that the code has issues:
- relying on current compat_msg_min[type] <= xfrm_msg_min[type]
- expected 4-byte padding size difference between
compat_msg_min[type] and xfrm_msg_min[type]
- compat_policy[type].len <= xfrma_policy[type].len
(for every type)

Reported-by: syzbot+834ffd1afc7212eb8147@syzkaller.appspotmail.com
Fixes: 5f3eea6b7e8f ("xfrm/compat: Attach xfrm dumps to 64=>32 bit translator")
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: netdev@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/xfrm/xfrm_compat.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

--- a/net/xfrm/xfrm_compat.c
+++ b/net/xfrm/xfrm_compat.c
@@ -216,7 +216,7 @@ static struct nlmsghdr *xfrm_nlmsg_put_c
case XFRM_MSG_GETSADINFO:
case XFRM_MSG_GETSPDINFO:
default:
- WARN_ONCE(1, "unsupported nlmsg_type %d", nlh_src->nlmsg_type);
+ pr_warn_once("unsupported nlmsg_type %d\n", nlh_src->nlmsg_type);
return ERR_PTR(-EOPNOTSUPP);
}

@@ -277,7 +277,7 @@ static int xfrm_xlate64_attr(struct sk_b
return xfrm_nla_cpy(dst, src, nla_len(src));
default:
BUILD_BUG_ON(XFRMA_MAX != XFRMA_IF_ID);
- WARN_ONCE(1, "unsupported nla_type %d", src->nla_type);
+ pr_warn_once("unsupported nla_type %d\n", src->nla_type);
return -EOPNOTSUPP;
}
}
@@ -315,8 +315,10 @@ static int xfrm_alloc_compat(struct sk_b
struct sk_buff *new = NULL;
int err;

- if (WARN_ON_ONCE(type >= ARRAY_SIZE(xfrm_msg_min)))
+ if (type >= ARRAY_SIZE(xfrm_msg_min)) {
+ pr_warn_once("unsupported nlmsg_type %d\n", nlh_src->nlmsg_type);
return -EOPNOTSUPP;
+ }

if (skb_shinfo(skb)->frag_list == NULL) {
new = alloc_skb(skb->len + skb_tailroom(skb), GFP_ATOMIC);
@@ -378,6 +380,10 @@ static int xfrm_attr_cpy32(void *dst, si
struct nlmsghdr *nlmsg = dst;
struct nlattr *nla;

+ /* xfrm_user_rcv_msg_compat() relies on fact that 32-bit messages
+ * have the same len or shorted than 64-bit ones.
+ * 32-bit translation that is bigger than 64-bit original is unexpected.
+ */
if (WARN_ON_ONCE(copy_len > payload))
copy_len = payload;