From 3ca339417067d054e73c352920f4964b7a673614 Mon Sep 17 00:00:00 2001
From: Konstantin Knizhnik <knizhnik@garret.ru>
Date: Thu, 5 Aug 2021 16:57:57 +0300
Subject: [PATCH] [refer #395] Check WAL record CRC in waldecoder (#396)

---
 pageserver/src/waldecoder.rs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/pageserver/src/waldecoder.rs b/pageserver/src/waldecoder.rs
index 10e66dac63..06ec502058 100644
--- a/pageserver/src/waldecoder.rs
+++ b/pageserver/src/waldecoder.rs
@@ -4,6 +4,7 @@
 //!
 use bytes::{Buf, BufMut, Bytes, BytesMut};
 use log::*;
+use crc32c::*;
 use postgres_ffi::pg_constants;
 use postgres_ffi::xlog_utils::*;
 use postgres_ffi::XLogLongPageHeaderData;
@@ -166,6 +167,14 @@ impl WalStreamDecoder {
                     // XLOG_SWITCH records are special. If we see one, we need to skip
                     // to the next WAL segment.
                     let xlogrec = XLogRecord::from_bytes(&mut buf);
+                    let mut crc = crc32c_append(0, &recordbuf[XLOG_RECORD_CRC_OFFS+4..]);
+                    crc = crc32c_append(crc, &recordbuf[0..XLOG_RECORD_CRC_OFFS]);
+                    if crc != xlogrec.xl_crc {
+                        return Err(WalDecodeError {
+                            msg: "WAL record crc mismatch".into(),
+                            lsn: self.lsn,
+                        });
+                    }
                     if xlogrec.is_xlog_switch_record() {
                         trace!("saw xlog switch record at {}", self.lsn);
                         self.padlen =