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fix(rdpdr): fix incorrect padding when parsing NDR strings #1015

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Merged
merged 1 commit into from
Oct 9, 2025
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fix(rdpdr): fix incorrect padding when parsing NDR strings #1015

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12 changes: 8 additions & 4 deletions crates/ironrdp-rdpdr/src/pdu/esc/ndr.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -80,17 +80,21 @@ pub fn ptr_size(with_length: bool) -> usize {
/// offset fields prefixing the string, as well as any extra padding for a 4-byte aligned
/// NULL-terminated string.
pub fn read_string_from_cursor(cursor: &mut ReadCursor<'_>, charset: CharacterSet) -> DecodeResult<String> {
const ALIGNMENT: usize = 4;
ensure_size!(ctx: "ndr::read_string_from_cursor", in: cursor, size: size_of::<u32>() * 3);
let length = cursor.read_u32();
let _length = cursor.read_u32();
let _offset = cursor.read_u32();
let _length2 = cursor.read_u32();

let string = utils::read_string_from_cursor(cursor, charset, true)?;

// Skip padding for 4-byte aligned NULL-terminated string.
if length % 2 != 0 {
ensure_size!(ctx: "ndr::read_string_from_cursor", in: cursor, size: size_of::<u16>());
let _padding = cursor.read_u16();
let mut pad = cursor.pos();
let size = (pad + ALIGNMENT - 1) & !(ALIGNMENT - 1);
pad = size - pad;
if pad > 0 {
ensure_size!(ctx: "ndr::read_string_from_cursor", in: cursor, size: pad);
cursor.advance(pad);
}

Ok(string)
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