CVE-2022-36114: limit the maximum unpacked size of a crate to 512MB

This gives users of custom registries the same protections, using the
same size limit that crates.io uses.

`LimitErrorReader` code copied from crates.io.

src/cargo/sources/registry/mod.rs

@@ -182,7 +182,9 @@ use crate::util::hex;
 use crate::util::interning::InternedString;
 use crate::util::into_url::IntoUrl;
 use crate::util::network::PollExt;
-use crate::util::{restricted_names, CargoResult, Config, Filesystem, OptVersionReq};
+use crate::util::{
+    restricted_names, CargoResult, Config, Filesystem, LimitErrorReader, OptVersionReq,
+};
 
 const PACKAGE_SOURCE_LOCK: &str = ".cargo-ok";
 pub const CRATES_IO_INDEX: &str = "https://github.com/rust-lang/crates.io-index";
@@ -194,6 +196,7 @@ const VERSION_TEMPLATE: &str = "{version}";
 const PREFIX_TEMPLATE: &str = "{prefix}";
 const LOWER_PREFIX_TEMPLATE: &str = "{lowerprefix}";
 const CHECKSUM_TEMPLATE: &str = "{sha256-checksum}";
+const MAX_UNPACK_SIZE: u64 = 512 * 1024 * 1024;
 
 /// A "source" for a local (see `local::LocalRegistry`) or remote (see
 /// `remote::RemoteRegistry`) registry.
@@ -615,6 +618,7 @@ impl<'cfg> RegistrySource<'cfg> {
             }
         }
         let gz = GzDecoder::new(tarball);
+        let gz = LimitErrorReader::new(gz, MAX_UNPACK_SIZE);
         let mut tar = Archive::new(gz);
         let prefix = unpack_dir.file_name().unwrap();
         let parent = unpack_dir.parent().unwrap();

src/cargo/util/io.rs

@@ -0,0 +1,27 @@
+use std::io::{self, Read, Take};
+
+#[derive(Debug)]
+pub struct LimitErrorReader<R> {
+    inner: Take<R>,
+}
+
+impl<R: Read> LimitErrorReader<R> {
+    pub fn new(r: R, limit: u64) -> LimitErrorReader<R> {
+        LimitErrorReader {
+            inner: r.take(limit),
+        }
+    }
+}
+
+impl<R: Read> Read for LimitErrorReader<R> {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        match self.inner.read(buf) {
+            Ok(0) if self.inner.limit() == 0 => Err(io::Error::new(
+                io::ErrorKind::Other,
+                "maximum limit reached when reading",
+            )),
+            e => e,
+        }
+    }
+}
+

src/cargo/util/mod.rs

@@ -14,6 +14,7 @@ pub use self::hasher::StableHasher;
 pub use self::hex::{hash_u64, short_hash, to_hex};
 pub use self::into_url::IntoUrl;
 pub use self::into_url_with_base::IntoUrlWithBase;
+pub(crate) use self::io::LimitErrorReader;
 pub use self::lev_distance::{closest, closest_msg, lev_distance};
 pub use self::lockserver::{LockServer, LockServerClient, LockServerStarted};
 pub use self::progress::{Progress, ProgressStyle};
@@ -44,6 +45,7 @@ pub mod important_paths;
 pub mod interning;
 pub mod into_url;
 mod into_url_with_base;
+mod io;
 pub mod job;
 pub mod lev_distance;
 mod lockserver;