[PATCH net-next] ethtool: tsconfig: reject zero-valued tx_type and rx_filter bitsets
From: Jakub Kicinski <kuba@kernel.org>
Date: 2026-08-12 16:22:32
Subsystem:
networking [ethtool], networking [general], the rest · Maintainers:
Andrew Lunn, Jakub Kicinski, "David S. Miller", Eric Dumazet, Paolo Abeni, Linus Torvalds
The ffs()/fls() guard in ethnl_set_tsconfig() was meant to enforce that the user selects exactly one tx_type (and one rx_filter) at a time (off / none are explicit types with non-zero values). However, both ffs(0) and fls(0) return 0, so the guard passes a zero-valued bitset through. The subsequent ffs(req_tx_type) - 1 would produce -1, if user selected no bit. net_hwtstamp_validate() catches the invalid -1 downstream, but returns a generic error (-ERANGE) without telling the user what went wrong. Return -EINVAL + extack instead. Replace the ffs()/fls() comparison with a hweight32() == 1 check. Signed-off-by: Jakub Kicinski <kuba@kernel.org> --- CC: andrew@lunn.ch CC: vadim.fedorenko@linux.dev --- net/ethtool/tsconfig.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/net/ethtool/tsconfig.c b/net/ethtool/tsconfig.c
index 24b64862011f..6be3aa5d4bc1 100644
--- a/net/ethtool/tsconfig.c
+++ b/net/ethtool/tsconfig.c@@ -359,8 +359,10 @@ static int ethnl_set_tsconfig(struct ethnl_req_info *req_base, if (ret < 0) goto err_free_hwprov; - /* Select only one tx type at a time */ - if (ffs(req_tx_type) != fls(req_tx_type)) { + /* Select exactly one tx type at a time */ + if (hweight32(req_tx_type) != 1) { + NL_SET_BAD_ATTR(info->extack, + tb[ETHTOOL_A_TSCONFIG_TX_TYPES]); ret = -EINVAL; goto err_free_hwprov; }
@@ -380,8 +382,10 @@ static int ethnl_set_tsconfig(struct ethnl_req_info *req_base, if (ret < 0) goto err_free_hwprov; - /* Select only one rx filter at a time */ - if (ffs(req_rx_filter) != fls(req_rx_filter)) { + /* Select exactly one rx filter at a time */ + if (hweight32(req_rx_filter) != 1) { + NL_SET_BAD_ATTR(info->extack, + tb[ETHTOOL_A_TSCONFIG_RX_FILTERS]); ret = -EINVAL; goto err_free_hwprov; }
--
2.55.0