Commit 3d042592 authored May 11, 2026 by Chenguang Zhao Committed by Jakub Kicinski May 12, 2026

ethtool: fix ethnl_bitmap32_not_zero() bit interval semantics



ethnl_bitmap32_not_zero() should return true if some bit in [start, end)
is set:

- Fix inverted memchr_inv() sense: return true when the scan finds a
  non-zero byte, not when the middle words are all zero.
- Return false for an empty interval (end <= start).
- When end is 32-bit aligned, indices in [start, end) do not include any
  bits from map[end_word]; return false after earlier checks found no
  non-zero data.

Fixes: 10b518d4 ("ethtool: netlink bitset handling")
Signed-off-by: Chenguang Zhao <zhaochenguang@kylinos.cn>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

parent 7bf563ba

net/ethtool/bitset.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -92,7 +92,7 @@ static bool ethnl_bitmap32_not_zero(const u32 *map, unsigned int start,
		u32 mask;

		if (end <= start)
		return true;
		return false;

		if (start % 32) {
		mask = ethnl_upper_bits(start);
		@@ -105,11 +105,11 @@ static bool ethnl_bitmap32_not_zero(const u32 *map, unsigned int start,
		start_word++;
		}

		if (!memchr_inv(map + start_word, '\0',
		if (memchr_inv(map + start_word, '\0',
		(end_word - start_word) * sizeof(u32)))
		return true;
		if (end % 32 == 0)
		return true;
		return false;
		return map[end_word] & ethnl_lower_bits(end);
		}