[PATCH] net: sock: correctly handle failed prog retrieval from fd

From: Sasha Levin
Date: Fri Dec 12 2014 - 00:34:20 EST

Commit "net: sock: allow eBPF programs to be attached to sockets" didn't
correctly handle the case where there is a failure getting the prog from
a given fd.

This allows for easy NULL ptr deref from userspace.

Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
net/core/filter.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index 8cc3c03..ec9baea 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 */

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