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

[Kangjie Lu]

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 <k...@umn.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