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Unsound `from` with misaligned pointer dereference

The source of unsoundness

hash-rs/src/sha1/mod.rs

Lines 12 to 17 in 96f5aa4

    
           let ptr = p.as_mut_ptr() as *mut u64; 
        
           let word = u64::to_be(m.len() as u64 * 8 as u64); 
        
           unsafe { 
        
               let p = (p.len()/8 - 1) as isize; 
        
               *ptr.offset(p) = word; 
        
           }

In line 12, the code tried to cast the raw pointer with 1-byte-alignment to the raw pointer with 8-byte-alignment, and this would create a misaligned pointer. In line 16, the code deref the misaligned pointer which is unsound. Similar unsoundness happened in following two places.

hash-rs/src/sha1/mod.rs

Lines 29 to 35 in 96f5aa4

    
           let output_ptr = digest.as_mut_ptr() as *mut u32; 
        
           for i in 0..state.len() { 
        
               let word = u32::to_be(state[i] as u32); 
        
               unsafe { 
        
                   *output_ptr.offset(i as isize) = word; 
        
               } 
        
           }

line 29: create misaligned pointer, line 33: dereference

hash-rs/src/sha3/mod.rs

Lines 32 to 38 in 96f5aa4

    
           let output_ptr = digest.as_mut_ptr() as *mut u64; 
        
           for i in 0..(OUTPUT_LEN / 8) { 
        
               let word = u64::to_le(state[i]); 
        
               unsafe { 
        
                   *output_ptr.offset(i as isize) = word; 
        
               } 
        
           }

line 32: create misaligned pointer, line 36: dereference

To reproduce the bug

use hash;

fn main() {
    let input = "hello";
    let digest = hash::Digest::sha1(&input.as_bytes());
    println!("{:?}", digest);
}

run with Miri

error: Undefined Behavior: accessing memory with alignment 1, but alignment 8 is required
  --> /{personal path}hash-rs-0.0.2/src/sha1/mod.rs:16:9
   |
16 |         *ptr.offset(p) = word;
   |         ^^^^^^^^^^^^^^^^^^^^^ accessing memory with alignment 1, but alignment 8 is required
   |

Undefined behavior should not happen with safe Rust function.

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	let ptr = p.as_mut_ptr() as *mut u64;
	let word = u64::to_be(m.len() as u64 * 8 as u64);
	unsafe {
	let p = (p.len()/8 - 1) as isize;
	*ptr.offset(p) = word;
	}

	let output_ptr = digest.as_mut_ptr() as *mut u32;
	for i in 0..state.len() {
	let word = u32::to_be(state[i] as u32);
	unsafe {
	*output_ptr.offset(i as isize) = word;
	}
	}

	let output_ptr = digest.as_mut_ptr() as *mut u64;
	for i in 0..(OUTPUT_LEN / 8) {
	let word = u64::to_le(state[i]);
	unsafe {
	*output_ptr.offset(i as isize) = word;
	}
	}

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