netdev - [PATCH] bpf: fix a missing check of return value

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Date:   Thu, 20 Dec 2018 13:45:56 -0600
From:   Kangjie Lu <kjlu@....edu>
To:     kjlu@....edu
Cc:     pakki001@....edu, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] bpf: fix a missing check of return value

check_reg_arg() may fail and not mark correct data in "env".  This
fix inserts a check that ensures check_reg_arg() is successful, and
if it is not, the fix stops further operations and returns an error
upstream.

Signed-off-by: Kangjie Lu <kjlu@....edu>
---
 kernel/bpf/verifier.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 51ba84d4d34a..ced8cc6470b1 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2619,7 +2619,9 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
 	/* after the call registers r0 - r5 were scratched */
 	for (i = 0; i < CALLER_SAVED_REGS; i++) {
 		mark_reg_not_init(env, caller->regs, caller_saved[i]);
-		check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
+		err = check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
+		if (err)
+			return err;
 	}
 
 	/* only increment it after check_reg_arg() finished */
-- 
2.17.1