On Tue, Oct 03, 2023 at 10:56:52AM +0200, Köry Maincent wrote:
> From: Kory Maincent <kory.maincent@xxxxxxxxxxx>
>
> 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. The commit
> 6699170376ab fixes this issue by clearing the whole target bitmap before we
> start iterating. The solution proposed brought an issue with the behavior
> of the mod variable. As the bitset is always cleared the old val will
> always differ to the new val.
>
> Fix it by adding a new temporary variable which save the state of the old
> bitmap.
>
> Fixes: 6699170376ab ("ethtool: fix application of verbose no_mask bitset")
> Signed-off-by: Kory Maincent <kory.maincent@xxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> net/ethtool/bitset.c | 25 +++++++++++++++++++------
> 1 file changed, 19 insertions(+), 6 deletions(-)
>
> diff --git a/net/ethtool/bitset.c b/net/ethtool/bitset.c
> index 0515d6604b3b..95f11b0a38b4 100644
> --- a/net/ethtool/bitset.c
> +++ b/net/ethtool/bitset.c
> @@ -432,7 +432,9 @@ ethnl_update_bitset32_verbose(u32 *bitmap, unsigned int nbits,
> struct netlink_ext_ack *extack, bool *mod)
> {
> struct nlattr *bit_attr;
> + u32 *tmp = NULL;
> bool no_mask;
> + bool dummy;
> int rem;
> int ret;
>
> @@ -448,8 +450,11 @@ ethnl_update_bitset32_verbose(u32 *bitmap, unsigned int nbits,
> }
>
> no_mask = tb[ETHTOOL_A_BITSET_NOMASK];
> - if (no_mask)
> - ethnl_bitmap32_clear(bitmap, 0, nbits, mod);
> + if (no_mask) {
> + tmp = kcalloc(nbits, sizeof(u32), GFP_KERNEL);
> + memcpy(tmp, bitmap, nbits);
Hi Köry,
I'm no expert on etnhl bitmaps. But the above doesn't seem correct to me.
Given that sizeof(u32) == 4:
* The allocation is for nbits * 4 bytes
* The copy is for its for nbits bytes
* I believe that bitmap contains space for the value followed by a mask.
So it seems to me the size of bitmap, in words, is
DIV_ROUND_UP(nbits, 32) * 2
And in bytes: DIV_ROUND_UP(nbits, 32) * 16
But perhaps only half is needed if only the value part of tmp is used.
If I'm on the right track here I'd suggest helpers might be in order.
> + ethnl_bitmap32_clear(bitmap, 0, nbits, &dummy);
> + }
>
> nla_for_each_nested(bit_attr, tb[ETHTOOL_A_BITSET_BITS], rem) {
> bool old_val, new_val;
> @@ -458,13 +463,18 @@ ethnl_update_bitset32_verbose(u32 *bitmap, unsigned int nbits,
> if (nla_type(bit_attr) != ETHTOOL_A_BITSET_BITS_BIT) {
> NL_SET_ERR_MSG_ATTR(extack, bit_attr,
> "only ETHTOOL_A_BITSET_BITS_BIT allowed in ETHTOOL_A_BITSET_BITS");
> - return -EINVAL;
> + ret = -EINVAL;
> + goto out;
> }
> ret = ethnl_parse_bit(&idx, &new_val, nbits, bit_attr, no_mask,
> names, extack);
> if (ret < 0)
> - return ret;
> - old_val = bitmap[idx / 32] & ((u32)1 << (idx % 32));
> + goto out;
> + if (no_mask)
> + old_val = tmp[idx / 32] & ((u32)1 << (idx % 32));
> + else
> + old_val = bitmap[idx / 32] & ((u32)1 << (idx % 32));
> +
> if (new_val != old_val) {
> if (new_val)
> bitmap[idx / 32] |= ((u32)1 << (idx % 32));
> @@ -474,7 +484,10 @@ ethnl_update_bitset32_verbose(u32 *bitmap, unsigned int nbits,
> }
> }
>
> - return 0;
> + ret = 0;
> +out:
> + kfree(tmp);
> + return ret;
> }
>
> static int ethnl_compact_sanity_checks(unsigned int nbits,
> --
> 2.25.1
>
>
