From 58509c75a2a2d472855da0683c36d7ef2f1a6c97 Mon Sep 17 00:00:00 2001
From: Dmitry Vyukov <dvyukov@google.com>
Date: Wed, 23 Dec 2015 19:58:15 +0100
Subject: prog: remove padding checking

So far it has found only false positives.
Let's leave this to KMSAN.
---
 executor/executor.cc | 56 ++--------------------------------------------------
 1 file changed, 2 insertions(+), 54 deletions(-)

(limited to 'executor/executor.cc')

diff --git a/executor/executor.cc b/executor/executor.cc
index 9cdeb7ab8..4b1b38968 100644
--- a/executor/executor.cc
+++ b/executor/executor.cc
@@ -47,8 +47,6 @@ const int kCoverSize = 16 << 10;
 const uint64_t instr_eof = -1;
 const uint64_t instr_copyin = -2;
 const uint64_t instr_copyout = -3;
-const uint64_t instr_set_pad = -4;
-const uint64_t instr_check_pad = -5;
 
 const uint64_t arg_const = 0;
 const uint64_t arg_result = 1;
@@ -314,17 +312,6 @@ retry:
 			// The copyout will happen when/if the call completes.
 			continue;
 		}
-		if (call_num == instr_set_pad) {
-			char* addr = (char*)read_input(&input_pos); // addr
-			uint64_t size = read_input(&input_pos);     // size
-			memset(addr, 0, size);
-			continue;
-		}
-		if (call_num == instr_check_pad) {
-			read_input(&input_pos); // addr
-			read_input(&input_pos); // size
-			continue;
-		}
 
 		// Normal syscall.
 		if (call_num >= sizeof(syscalls) / sizeof(syscalls[0]))
@@ -443,7 +430,6 @@ void handle_completion(thread_t* th)
 	if (th->ready || !th->done || th->handled)
 		fail("bad thread state in completion: ready=%d done=%d handled=%d",
 		     th->ready, th->done, th->handled);
-	uint64_t* copyout_pos = th->copyout_pos;
 	if (th->res != (uint64_t)-1) {
 		results[th->call_n].executed = true;
 		results[th->call_n].val = th->res;
@@ -460,12 +446,6 @@ void handle_completion(thread_t* th)
 				debug("copyout from %p\n", addr);
 				break;
 			}
-			case instr_check_pad: {
-				// Ignore for now, we will process them below.
-				read_input(&th->copyout_pos);
-				read_input(&th->copyout_pos);
-				break;
-			}
 			default:
 				done = true;
 				break;
@@ -473,39 +453,6 @@ void handle_completion(thread_t* th)
 		}
 	}
 	if (!collide) {
-		th->copyout_pos = copyout_pos;
-		for (bool done = false; !done;) {
-			uint64_t call_num = read_input(&th->copyout_pos);
-			switch (call_num) {
-			case instr_copyout: {
-				// Ignore, this is already handled above.
-				read_input(&th->copyout_pos);
-				read_input(&th->copyout_pos);
-				break;
-			}
-			case instr_check_pad: {
-				// Check that kernel returns zeros in struct padding.
-				// Non-zeros can mean an information leak.
-				char* addr = (char*)read_input(&th->copyout_pos);
-				uint64_t size = read_input(&th->copyout_pos);
-				for (uint64_t i = 0; i < size; i++) {
-					if (addr[i] != 0) {
-						printf("syscall '%s' (index %d): non-zero padding output at %p:",
-						       syscalls[th->call_num].name, th->call_index, addr);
-						for (i = 0; i < size; i++)
-							printf(" %02x", addr[i]);
-						printf("\n");
-						error("non-zero padding");
-					}
-				}
-				break;
-			}
-			default:
-				done = true;
-				break;
-			}
-		}
-
 		write_output(th->call_index);
 		write_output(th->call_num);
 		write_output(th->res != (uint64_t)-1 ? 0 : th->reserrno);
@@ -842,12 +789,13 @@ void error(const char* msg, ...)
 // just exit (e.g. due to temporal ENOMEM error)
 void exitf(const char* msg, ...)
 {
+	int e = errno;
 	fflush(stdout);
 	va_list args;
 	va_start(args, msg);
 	vfprintf(stderr, msg, args);
 	va_end(args);
-	fprintf(stderr, "\n");
+	fprintf(stderr, " (errno %d)\n", e);
 	exit(1);
 }
 
-- 
cgit mrf-deployment