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avb: Use checked addition when computing auth/aux block size #163

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merged 1 commit into from
Sep 28, 2023
Merged

avb: Use checked addition when computing auth/aux block size #163

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13 changes: 9 additions & 4 deletions avbroot/src/format/avb.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1650,9 +1650,11 @@ impl<R: Read> FromReader<R> for Header {
let signature_offset = reader.read_u64::<BigEndian>()?;
let signature_size = reader.read_u64::<BigEndian>()?;

let auth_block_combined = hash_size + signature_size;
let auth_block_combined = hash_size
.checked_add(signature_size)
.ok_or_else(|| Error::FieldOutOfBounds("auth_block_combined"))?;
let auth_block_padding = padding::calc(auth_block_combined, 64);
if auth_block_size != auth_block_combined + auth_block_padding {
if auth_block_combined.checked_add(auth_block_padding) != Some(auth_block_size) {
return Err(Error::FieldOutOfBounds("auth_block_size"));
} else if hash_offset > auth_block_combined - hash_size {
return Err(Error::FieldOutOfBounds("hash_offset"));
Expand All @@ -1667,9 +1669,12 @@ impl<R: Read> FromReader<R> for Header {
let descriptors_offset = reader.read_u64::<BigEndian>()?;
let descriptors_size = reader.read_u64::<BigEndian>()?;

let aux_block_combined = public_key_size + public_key_metadata_size + descriptors_size;
let aux_block_combined = public_key_size
.checked_add(public_key_metadata_size)
.and_then(|s| s.checked_add(descriptors_size))
.ok_or_else(|| Error::FieldOutOfBounds("aux_block_combined"))?;
let aux_block_padding = padding::calc(aux_block_combined, 64);
if aux_block_size != aux_block_combined + aux_block_padding {
if aux_block_combined.checked_add(aux_block_padding) != Some(aux_block_size) {
return Err(Error::FieldOutOfBounds("aux_block_size"));
} else if public_key_offset > aux_block_combined - public_key_size {
return Err(Error::FieldOutOfBounds("public_key_offset"));
Expand Down