linux-kernel - [PATCH v2 1/2] lib: decompress

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Message-Id: <20200825210127.17850-1-paul@crapouillou.net>
Date:   Tue, 25 Aug 2020 23:01:26 +0200
From:   Paul Cercueil <paul@...pouillou.net>
To:     Nick Terrell <terrelln@...com>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc:     linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        od@...c.me, Paul Cercueil <paul@...pouillou.net>
Subject: [PATCH v2 1/2] lib: decompress_unzstd: Limit output size

The zstd decompression code, as it is right now, will have internal
values overflow on 32-bit systems when the output size is bigger than
1 GiB.

Until someone smarter than me can figure out how to fix the zstd code
properly, limit the destination buffer size to 1 GiB, which should be
enough for everybody, in order to make it usable on 32-bit systems.

Signed-off-by: Paul Cercueil <paul@...pouillou.net>
Reviewed-by: Nick Terrell <terrelln@...com>
---

Notes:
    v2: Change limit to 1 GiB

 lib/decompress_unzstd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/decompress_unzstd.c b/lib/decompress_unzstd.c
index 0ad2c15479ed..414517baedb0 100644
--- a/lib/decompress_unzstd.c
+++ b/lib/decompress_unzstd.c
@@ -77,6 +77,7 @@
 
 #include <linux/decompress/mm.h>
 #include <linux/kernel.h>
+#include <linux/sizes.h>
 #include <linux/zstd.h>
 
 /* 128MB is the maximum window size supported by zstd. */
@@ -179,7 +180,7 @@ static int INIT __unzstd(unsigned char *in_buf, long in_len,
 	size_t ret;
 
 	if (out_len == 0)
-		out_len = LONG_MAX; /* no limit */
+		out_len = SZ_1G; /* should be big enough, right? */
 
 	if (fill == NULL && flush == NULL)
 		/*
-- 
2.28.0