From 63f4bfd6ac486fc585c1df8f063586d26487bec6 Mon Sep 17 00:00:00 2001
From: Rich Ercolani <214141+rincebrain@users.noreply.github.com>
Date: Wed, 12 Jan 2022 19:14:36 -0500
Subject: [PATCH] lz4: Cherrypick fix for CVE-2021-3520

There should be no risk of us accidentally hitting this since
we'd need maliciously malformed data to wind up in the pipeline,
or a very unfortunate random bit flip at exactly the right moment.
Still since we can handle it we should.

Reviewed-by: Igor Kozhukhov <igor@dilos.org>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Adam Moss <c@yotes.com>
Signed-off-by: Rich Ercolani <rincebrain@gmail.com>
Closes #12947
---
 module/zfs/lz4.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/module/zfs/lz4.c b/module/zfs/lz4.c
index 800635b344..75a31bf17e 100644
--- a/module/zfs/lz4.c
+++ b/module/zfs/lz4.c
@@ -541,7 +541,7 @@ LZ4_decompress_generic(
                  const size_t dictSize         /* note : = 0 if noDict */
                  )
 {
-    if (src == NULL) { return -1; }
+    if ((src == NULL) || (outputSize < 0)) { return -1; }
 
     {   const BYTE* ip = (const BYTE*) src;
         const BYTE* const iend = ip + srcSize;