Enum Padding 

pub enum Padding {
    Ignored,
    Tracked,
}

Whether padding participates in the init plane, from -fsafety-init=.

Design: spec/safe-memory/09-type-init-and-races.md section 9.3.

The correct rule is that a store which writes an object as a whole initializes it as a whole, padding included, and that a fill done a member at a time leaves the padding alone. That rule reports a structure filled member by member and then hashed, compared or written to a file, and it is right to: that is CWE-200 and it is the kernel infoleak KMSAN was built to find.

It is also every third program in a userspace corpus, where the bytes never leave the process and nobody is hunting an infoleak. So section 9.3 makes it a flag and splits the default: padding participates for the kernel profile, where the leak is the thing being looked for, and does not for library code, where it would be a torrent of reports about programs nobody is worried about. Document 12’s scoreboard reports the two configurations separately for the same reason.

Variants

Ignored

-fsafety-init=nopadding. A store through a member says the padding after it holds something too, so a record filled a member at a time comes out entirely written.

Tracked

-fsafety-init=padding. A store through a member says only what it wrote, which is section 9.3’s rule and is what makes the infoleak visible.

Implementations

impl Padding

pub const fn as_str(self) -> &'static str

The spelling this is asked for by, without the flag in front of it.

Trait Implementations

impl Clone for Padding

fn clone(&self) -> Padding

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Padding

impl Debug for Padding

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Padding

fn default() -> Padding

Returns the “default value” for a type.

impl Display for Padding

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for Padding

impl FromStr for Padding

fn from_str(s: &str) -> Result<Self, ()>

Parses the part after -fsafety-init=.

type Err = ()

The associated error which can be returned from parsing.

impl Hash for Padding

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for Padding

fn cmp(&self, other: &Padding) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

fn clamp_to<R>(self, range: R) -> Self

where Self: Sized, R: ClampBounds<Self>,

🔬This is a nightly-only experimental API. (clamp_to)

Restrict a value to a certain range.

impl PartialEq for Padding

fn eq(&self, other: &Padding) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialOrd for Padding

fn partial_cmp(&self, other: &Padding) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl StructuralPartialEq for Padding