netfilter: nft_set_rbtree: fix bogus EEXIST with NLM_F_CREATE with null interval

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[ Upstream commit 7f9203f41a ]

Userspace adds a non-matching null element to the kernel for historical
reasons. This null element is added when the set is populated with
elements. Inclusion of this element is conditional, therefore,
userspace needs to dump the set content to check for its presence.

If the NLM_F_CREATE flag is turned on, this becomes an issue because
kernel bogusly reports EEXIST.

Add special case to ignore NLM_F_CREATE in this case, therefore,
re-adding the nul-element never fails.

Fixes: c016c7e45d ("netfilter: nf_tables: honor NLM_F_EXCL flag in set element insertion")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

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Pablo Neira Ayuso 2026-02-06 13:33:43 +01:00 • committed by Sasha Levin

parent 4f899976ee

commit afe1a28fa9

2 changed files with 18 additions and 0 deletions

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5

net/netfilter/nf_tables_api.c

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13

net/netfilter/nft_set_rbtree.c

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