lib: decompress_unzstd: Limit output size

The zstd decompression code, as it is right now, will most likely fail on 32-bit systems, as the default output buffer size causes the buffer's end address to overflow. Address this issue by setting a sane default to the default output size, with a value that won't overflow the buffer's end address. Signed-off-by: Paul Cercueil <[email protected]> Reviewed-by: Nick Terrell <[email protected]> Signed-off-by: Thomas Bogendoerfer <[email protected]>
wafgo · Sep 3, 2020 · 1c4dd33 · 1c4dd33
1 parent aa9c45d
commit 1c4dd33
Showing 1 changed file with 6 additions and 1 deletion.
diff --git a/lib/decompress_unzstd.c b/lib/decompress_unzstd.c
@@ -178,8 +178,13 @@ static int INIT __unzstd(unsigned char *in_buf, long in_len,
 	int err;
 	size_t ret;
 
+	/*
+	 * ZSTD decompression code won't be happy if the buffer size is so big
+	 * that its end address overflows. When the size is not provided, make
+	 * it as big as possible without having the end address overflow.
+	 */
 	if (out_len == 0)
-		out_len = LONG_MAX; /* no limit */
+		out_len = UINTPTR_MAX - (uintptr_t)out_buf;
 
 	if (fill == NULL && flush == NULL)
 		/*