Subject: [PATCH bpf-next] bpf: fix bpf_attr.attach_btf_id check

From: Alexei Starovoitov <[email-masked]>
Date: Thu, 17 Oct 2019 23:09:33 -0700

Only raw_tracepoint program type can have bpf_attr.attach_btf_id >= 0.
Make sure to reject other program types that accidentally set it to non-zero.

Fixes: ccfe29eb29c2 ("bpf: Add attach_btf_id attribute to program load")
Reported-by: Andrii Nakryiko <[email-masked]>
Signed-off-by: Alexei Starovoitov <[email-masked]>
---
 kernel/bpf/syscall.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 523e3ac15a08..16ea3c0db4f6 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1570,6 +1570,17 @@ bpf_prog_load_check_attach(enum bpf_prog_type prog_type,
 			   enum bpf_attach_type expected_attach_type,
 			   u32 btf_id)
 {
+	switch (prog_type) {
+	case BPF_PROG_TYPE_RAW_TRACEPOINT:
+		if (btf_id > BTF_MAX_TYPE)
+			return -EINVAL;
+		break;
+	default:
+		if (btf_id)
+			return -EINVAL;
+		break;
+	}
+
 	switch (prog_type) {
 	case BPF_PROG_TYPE_CGROUP_SOCK:
 		switch (expected_attach_type) {
@@ -1610,13 +1621,7 @@ bpf_prog_load_check_attach(enum bpf_prog_type prog_type,
 		default:
 			return -EINVAL;
 		}
-	case BPF_PROG_TYPE_RAW_TRACEPOINT:
-		if (btf_id > BTF_MAX_TYPE)
-			return -EINVAL;
-		return 0;
 	default:
-		if (btf_id)
-			return -EINVAL;
 		return 0;
 	}
 }
-- 
2.17.1