uucore parse_size: arithmetic overflow (overflow-checks) on a large `%` (percent-of-memory) size

[leeewee]

uucore's shared size parser (parse_size.rs) supports a % suffix meaning "this percentage of physical memory". It computes (value / 100) * total_physical_memory as an unchecked u128 multiply. A % value large enough to fit in u128 but whose product exceeds u128::MAX overflows, panicking with attempt to multiply with overflow under -C overflow-checks (exit 134);

coreutils/src/uucore/src/lib/features/parser/parse_size.rs

Lines 253 to 260 in 89bdbb8

	// Special case: for percentage, just compute the given fraction
	// of the total physical memory on the machine, if possible.
	if unit == "%" {
	let number: u128 = Self::parse_number(&numeric_string, 10, size)?;
	return match total_physical_memory() {
	Ok(total) => Ok((number / 100) * total),
	Err(_) => Err(ParseSizeError::PhysicalMem(size.to_string())),
	};

Because it is shared code with a wide-open default, the panic is reachable from many utils, like du.

$ mkdir -p /tmp/dutest

$ du --block-size=9223372036854775808000000000000% /tmp/dutest
thread 'main' panicked at src/uucore/src/lib/features/parser/parse_size.rs:258:33:
attempt to multiply with overflow
$ echo $?
134

$ DU_BLOCK_SIZE=9223372036854775808000000000000% du /tmp/dutest   # same panic via env

The same % value (N = 9223372036854775808000000000000%) panics at parse_size.rs:258:33 from every command below.

util	command that triggers the panic	GNU exit
du	du --block-size=$N /tmp (also DU_BLOCK_SIZE=$N du /tmp)	0/1
sort	printf 'b\na\n' > f; sort -S $N f	2
df	df --block-size=$N	1
ls	ls --block-size=$N /tmp	2
split	printf 'x\n' > f; split -b $N f	1
stdbuf	stdbuf -o$N true	125
od	printf 'x' > f; od -N$N f	1
shred	printf 'x' > f; shred --size=$N f	1
dd	dd bs=$N (also count=$N, ibs=/obs=/seek=/skip=)	1
head	printf 'x' > f; head -c $N f	1
tail	printf 'x' > f; tail -c $N f	1

[RenjiSann]

Should be relatively easy to fix by using checked_mul I think