From: Colin Ian King <colin.king@canonical.com>
Date: Tue, 13 Nov 2018 09:29:26 +0000 (+0000)
Subject: bpf: fix null pointer dereference on pointer offload
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=592ee43faf860c1f2c0a4c11838db6fdb974bb78;p=openwrt%2Fstaging%2Fblogic.git

bpf: fix null pointer dereference on pointer offload

Pointer offload is being null checked however the following statement
dereferences the potentially null pointer offload when assigning
offload->dev_state.  Fix this by only assigning it if offload is not
null.

Detected by CoverityScan, CID#1475437 ("Dereference after null check")

Fixes: 00db12c3d141 ("bpf: call verifier_prep from its callback in struct bpf_offload_dev")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---

diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c
index 52c5617e3716..54cf2b9c44a4 100644
--- a/kernel/bpf/offload.c
+++ b/kernel/bpf/offload.c
@@ -130,9 +130,10 @@ int bpf_prog_offload_verifier_prep(struct bpf_prog *prog)
 
 	down_read(&bpf_devs_lock);
 	offload = prog->aux->offload;
-	if (offload)
+	if (offload) {
 		ret = offload->offdev->ops->prepare(prog);
-	offload->dev_state = !ret;
+		offload->dev_state = !ret;
+	}
 	up_read(&bpf_devs_lock);
 
 	return ret;