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std: reject interior NULs in Windows junction_point target path #594

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std: reject interior NULs in Windows junction_point target path #594

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14 changes: 14 additions & 0 deletions library/std/src/sys/fs/windows.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1645,6 +1645,14 @@ pub fn junction_point(original: &Path, link: &Path) -> io::Result<()> {

// We need to get an absolute, NT-style path.
let path_bytes = original.as_os_str().as_encoded_bytes();
// Interior NULs in the target would truncate the reparse substitute name
// (same class of bug as chdir / AF_UNIX without to_u16s).
if path_bytes.contains(&0) {
return Err(io::const_error!(
io::ErrorKind::InvalidInput,
"strings passed to WinAPI cannot contain NULs",
));
}
let abs_path: Vec<u16> = if path_bytes.starts_with(br"\\?\") || path_bytes.starts_with(br"\??\")
{
// It's already an absolute path, we just need to convert the prefix to `\??\`
Expand All @@ -1653,6 +1661,12 @@ pub fn junction_point(original: &Path, link: &Path) -> io::Result<()> {
} else {
// Get an absolute path and then convert the prefix to `\??\`
let abs_path = crate::path::absolute(original)?.into_os_string().into_encoded_bytes();
if abs_path.contains(&0) {
return Err(io::const_error!(
io::ErrorKind::InvalidInput,
"strings passed to WinAPI cannot contain NULs",
));
}
if abs_path.len() > 0 && abs_path[1..].starts_with(br":\") {
let bytes = unsafe { OsStr::from_encoded_bytes_unchecked(&abs_path) };
r"\??\".encode_utf16().chain(bytes.encode_wide()).collect()
Expand Down