From: Alexei Starovoitov <ast@plumgrid.com>
Date: Thu, 11 Dec 2014 04:14:55 +0000 (-0800)
Subject: net: sock: fix access via invalid file descriptor
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=198bf1b046e370a7d3987b195cff5f1efebec3ac;p=openwrt%2Fstaging%2Fblogic.git

net: sock: fix access via invalid file descriptor

0day robot reported the following crash:
[   21.233581] BUG: unable to handle kernel NULL pointer dereference at 0000000000000007
[   21.234709] IP: [<ffffffff8156ebda>] sk_attach_bpf+0x39/0xc2

It's due to bpf_prog_get() returning ERR_PTR.
Check it properly.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Fixes: 89aa075832b0 ("net: sock: allow eBPF programs to be attached to sockets")
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/core/filter.c b/net/core/filter.c
index 8cc3c03078b3..ec9baea10c16 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1103,8 +1103,8 @@ int sk_attach_bpf(u32 ufd, struct sock *sk)
 		return -EPERM;
 
 	prog = bpf_prog_get(ufd);
-	if (!prog)
-		return -EINVAL;
+	if (IS_ERR(prog))
+		return PTR_ERR(prog);
 
 	if (prog->aux->prog_type != BPF_PROG_TYPE_SOCKET_FILTER) {
 		/* valid fd, but invalid program type */