[PATCH] bpf: fix missing checks of the return value of check_reg_arg

[Kangjie Lu]

check_reg_arg() may fail. This fix inserts checks for its return value.
If check_reg_arg() fails, issues an error message.

Signed-off-by: Kangjie Lu <k...@umn.edu>
---
 kernel/bpf/verifier.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 51ba84d4d34a..fde91a5c0b5a 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2619,7 +2619,10 @@ 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)
+                       verbose(env,
+                                       "check_reg_arg() fails in setting 
caller saved regs\n");
        }
 
        /* only increment it after check_reg_arg() finished */
@@ -2842,7 +2845,10 @@ static int check_helper_call(struct bpf_verifier_env 
*env, int func_id, int insn
        /* reset caller saved regs */
        for (i = 0; i < CALLER_SAVED_REGS; i++) {
                mark_reg_not_init(env, 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)
+                       verbose(env,
+                               "check_reg_arg() fails in resetting caller 
saved regs\n");
        }
 
        /* update return register (already marked as written above) */
@@ -4435,7 +4441,10 @@ static int check_ld_abs(struct bpf_verifier_env *env, 
struct bpf_insn *insn)
        /* reset caller saved regs to unreadable */
        for (i = 0; i < CALLER_SAVED_REGS; i++) {
                mark_reg_not_init(env, 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)
+                       verbose(env,
+                               "check_reg_arg() fails in resetting caller 
saved regs to unreadable\n");
        }
 
        /* mark destination R0 register as readable, since it contains
-- 
2.17.2 (Apple Git-113)