Why Rust? by Edd Barrett (codeHarbour December 2019)

A Little About Me
e ResearchAssociate @King’s College London
e Former postgrad of University of Kent.
e OpenBSD Developer (ports)
@ebarrett@mastodon.social @vext01

C and C++
C
e 1972
e Dennis Ritchie, Bell Labs
C++
e 1985
e Bjarne Stroustrup
Both “systems” languages.

C and C++ arePopular Languages
https://www.tiobe.com/tiobe-
index/

C and C++ arePopular Languages
https://thenewstack.io/evolve -die-popular -programming-languages-confront-newcom ers-tiobe-
index/

The problem languages like C and C++

Unsafe

Unsafe
e Memorysafety
e Threadsafety

Memory Safety
* s ) {v o i d d o _ s t u f f ( c h a r
. . .
i f ( e r r o r )
f r e e ( s ) ;
}
i n t m a i n ( v o i d ) {
c h a r * s = m a l l o c ( 1 6 ) ;
s t r n c p y ( s , " h e l l o " , 1 6 ) ;
p r i n t f ( " s= ’ s’ n " , s ) ;
d o _ s t u f f ( s ) ;
p r i n t f ( " s= ’ s’ n " , s ) ; / / < - - Use a f t e r f r e e !
r e t u r n ( EXIT_ SUCCESS ) ;
}

Kinds of Memory Error
e Useafter free
e Double free
e Buffer overflow
e Dangling pointer
e Freeinganinvalidaddress
Experiencedprogrammers makethesemistakes!

Memory Errors = Undefined Behaviour
What should happen afterwards is notdefined!
e Program may continue to work OK (you got
lucky)
e Program may crash
e Program my continue, but behave differently

Memory Safety
$ ./use-after -free
s=’hello ’
s=’ ’

*Not anaccuratedepiction of a hacker
https://pixabay.com/phot os/ hacker -attack-mask-internet-2883632/

Hackers!
“Hackers” exploit memory errors
Often they can“persuade” abrokenprogram to do
their bidding

What Hackers Want
e To steal your sensitive data.

What Hackers Want
e To steal your sensitive data.
e To run naughty programs on your computer.

CVEs
Common Vulnerability and Exposures
Database

https://nvd.nist.gov/ vuln/detail/CVE -2019-8225

CVE Statistics: Cifuentes andBierman
http:
//drops.dagstuhl.de/opus/volltexte/2019/10546/

CVE Statistics: Cifuentes andBierman
For the five years from 2013 to 2017: 5,899
buffer errors
(That’s about 21%of the data)
Average total cost of a data breach:
US$3.86 million

Other Statistics: Alex Gaynor
https://alexgaynor.net/2019/aug/12/
introduction-to-memory-unsafety-for-vps-of-engineering/

Other Statistics: Alex Gaynor
A recent study found that 60-70% of vul-
nerabilities in iOS and macOS are caused
by memory unsafety.
Microsoft estimates that 70% of all vulnera-
bilities in their products over the last decade
have been caused by memoryunsafety.
Google estimated that 90% of Android vul-
nerabilities arememoryunsafety.

How bad is the problem?
Pretty bad!

What can wedo?
e Detect and fix using dynamic/static analysis

What can wedo?
e OS-level mitigations

What can wedo?
e OS-level mitigations
e Usea“managed” language
e GarbageCollection :(

Rust’s Motivation
Rust’s rich type system and ownership
model guarantee memory-safety and
thread-safety, and enable you to eliminate
many classes of bugs at compile-time.
(+ performance + productivity)

Example: Use after Free in Rust
fn do_stuff(s: String) {
...
if error {
drop(s); // Not necessary.
}
}
fn main () {
let s = String ::from("hello");
println!("s=’{}’", s);
do_stuff(s);
println!("s=’{}’", s);
}

Example: Use after Free in Rust
e r r o r [ E0382 ] : borrow o f moved v a l u e : ‘s‘
l e t s
- - > s r c / m a i n . r s : 1 2 : 2 4
|
8 |
|
|
|
= S t r i n g : : from ( " h e l l o " ) ;
- move o c c u r s b e c a u s e ‘s‘h a s t y p e ‘s t d : :
s t r i n g : : S t r i n g ‘, which does n o t
i m p l e m e n t t h e ‘Copy ‘ t r a i t
d o _ s t u f f ( s ) ;
- v a l u e moved h e r e
p r i n t l n ! ( " s= ’{}’",
he r e
. . .
11 |
|
12 |
|
|
s ) ;
^ v a l u e borrowe d
a f t e r move
e r r o r : a b o r t i n g due t o p r e v i o u s e r r o r

Rust’s Ownership and Lifetimes
Compile-time memorysafety without agarbage
collector.

Rust’s Ownership and Lifetimes
Compile-time memorysafety without agarbage
collector.
Secureand performant systemsprogramming!

The take away message
With Rust, memoryerrors canbe(mostly) athing
of the past.

The take away message
With Rust, memoryerrors canbe(mostly) athing
of the past.
https://pixabay.com/photos/thumbs -up-thumb-hand-positive-

What else is good about Rust?
e Pretty good performance.

e Goodstandard library.

e Goodand safemulti-threading support.

e Pretty portable.

e Pretty portable.
e Thriving community and ecosystem.

Any Downsides?
e Rust is quite hard to learn.
e
e
e
Ownership/lifetimes are unfamiliar.
Error messages hard to understand.
Large language.

Any Downsides?
e
e
e
Large language.
e Rust is still young and changing.

Any Downsides?
e
e
e
Large language.
e Compile-times canbeslow.

Any Downsides?
e
e
e
Large language.
e Compile-times canbeslow.
e Somethings arequite hard in “safe” Rust.
e unsafe keyword

Resources
Website:
https://www.rust-lang.org/
GitHub:
https://github.com/rust-lang/rust
Try it out online:
https://play.rust-lang.org/
Learn:
https://doc.rust-lang.org/rust-by-example/

Why Rust? by Edd Barrett (codeHarbour December 2019)

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