[PATCH net] ethtool: fix application of verbose no_mask bitset

[Michal Kubecek <mkubecek@suse.cz>]

A bitset without mask in a _SET request means we want exactly the bits in
the bitset to be set. This works correctly for compact format but when
verbose format is parsed, ethnl_update_bitset32_verbose() only sets the
bits present in the request bitset but does not clear the rest. This can
cause incorrect results like

  lion:~ # ethtool eth0 | grep Wake
          Supports Wake-on: pumbg
          Wake-on: g
  lion:~ # ethtool -s eth0 wol u
  lion:~ # ethtool eth0 | grep Wake
          Supports Wake-on: pumbg
          Wake-on: ug

when the second ethtool command issues request

ETHTOOL_MSG_WOL_SET
    ETHTOOL_A_WOL_HEADER
        ETHTOOL_A_HEADER_DEV_NAME = "eth0"
    ETHTOOL_A_WOL_MODES
        ETHTOOL_A_BITSET_NOMASK
        ETHTOOL_A_BITSET_BITS
            ETHTOOL_A_BITSET_BITS_BIT
                ETHTOOL_BITSET_BIT_INDEX = 1

Fix the logic by clearing the whole target bitmap before we start iterating
through the request bits.

Fixes: 10b518d4e6dd ("ethtool: netlink bitset handling")
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
---
 net/ethtool/bitset.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/ethtool/bitset.c b/net/ethtool/bitset.c
index fce45dac4205..8977fe1f3946 100644
--- a/net/ethtool/bitset.c
+++ b/net/ethtool/bitset.c
@@ -447,7 +447,10 @@ ethnl_update_bitset32_verbose(u32 *bitmap, unsigned int nbits,
 				    "mask only allowed in compact bitset");
 		return -EINVAL;
 	}
+
 	no_mask = tb[ETHTOOL_A_BITSET_NOMASK];
+	if (no_mask)
+		ethnl_bitmap32_clear(bitmap, 0, nbits, mod);
 
 	nla_for_each_nested(bit_attr, tb[ETHTOOL_A_BITSET_BITS], rem) {
 		bool old_val, new_val;
-- 
2.25.0