Patch "ethtool: Fix mod state of verbose no_mask bitset" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    ethtool: Fix mod state of verbose no_mask bitset

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ethtool-fix-mod-state-of-verbose-no_mask-bitset.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit aa33590a57ca33b47f9f686d021f74ad53c26cd8
Author: Kory Maincent <kory.maincent@xxxxxxxxxxx>
Date:   Mon Oct 9 15:36:45 2023 +0200

    ethtool: Fix mod state of verbose no_mask bitset
    
    [ Upstream commit 108a36d07c01edbc5942d27c92494d1c6e4d45a0 ]
    
    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>
    Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20231009133645.44503-1-kory.maincent@xxxxxxxxxxx
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/ethtool/bitset.c b/net/ethtool/bitset.c
index 0515d6604b3b9..883ed9be81f9f 100644
--- a/net/ethtool/bitset.c
+++ b/net/ethtool/bitset.c
@@ -431,8 +431,10 @@ ethnl_update_bitset32_verbose(u32 *bitmap, unsigned int nbits,
 			      ethnl_string_array_t names,
 			      struct netlink_ext_ack *extack, bool *mod)
 {
+	u32 *orig_bitmap, *saved_bitmap = NULL;
 	struct nlattr *bit_attr;
 	bool no_mask;
+	bool dummy;
 	int rem;
 	int ret;
 
@@ -448,8 +450,22 @@ 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) {
+		unsigned int nwords = DIV_ROUND_UP(nbits, 32);
+		unsigned int nbytes = nwords * sizeof(u32);
+
+		/* The bitmap size is only the size of the map part without
+		 * its mask part.
+		 */
+		saved_bitmap = kcalloc(nwords, sizeof(u32), GFP_KERNEL);
+		if (!saved_bitmap)
+			return -ENOMEM;
+		memcpy(saved_bitmap, bitmap, nbytes);
+		ethnl_bitmap32_clear(bitmap, 0, nbits, &dummy);
+		orig_bitmap = saved_bitmap;
+	} else {
+		orig_bitmap = bitmap;
+	}
 
 	nla_for_each_nested(bit_attr, tb[ETHTOOL_A_BITSET_BITS], rem) {
 		bool old_val, new_val;
@@ -458,13 +474,14 @@ 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;
+		old_val = orig_bitmap[idx / 32] & ((u32)1 << (idx % 32));
 		if (new_val != old_val) {
 			if (new_val)
 				bitmap[idx / 32] |= ((u32)1 << (idx % 32));
@@ -474,7 +491,10 @@ ethnl_update_bitset32_verbose(u32 *bitmap, unsigned int nbits,
 		}
 	}
 
-	return 0;
+	ret = 0;
+out:
+	kfree(saved_bitmap);
+	return ret;
 }
 
 static int ethnl_compact_sanity_checks(unsigned int nbits,