From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C79511AF0AF; Mon, 9 Feb 2026 14:33:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770647624; cv=none; b=g5Z8ZUUEB5QhvUl1Eflv/5tGKwWbax5qQMk39LFZY0Jm49L95vKVbowhVadgYMD7GCxr6+CZuG1du576fw2K2KwUiRYmwDSdG+vtc/27m/d27cQh45/4CsmussgM+ZplA9oDhgM0Huggsh+RVgdI2vdcEzn4TN93tYkv9QMIa+E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770647624; c=relaxed/simple; bh=+ay1AvA4TogwB2pnuk+mZXvQbJ/SOh2hVRQZLBEPiN8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OFOaD7X68BD4EoKD8UWwJ7mMq7kyG3rM39OUzEuyfGe9k9JF4YKt8bwAM78HGwYnkIbskRJpny4PF6A6/ZEHzR9fwB/IlurRiWB4ljXQPbGBQzuVWRS1DYdBcvPQMZ8hwwh3hJRkuom/LHoehGPB7T8SVmScWL7wIJ0ruxqJQho= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=L2unqeNr; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="L2unqeNr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3ABACC116C6; Mon, 9 Feb 2026 14:33:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1770647624; bh=+ay1AvA4TogwB2pnuk+mZXvQbJ/SOh2hVRQZLBEPiN8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=L2unqeNryX7sZJe8dHkcK85iuvZZwK/Z96RKn+uDbxlVvHTAHdJKtEfO+qfYv9BOQ UrFYwCOTaCp5qStVIBNhtePHBSDkRD5fjYbEhTxUJQzaJVmn/aR+lTddlwdH4gAyPH Z5rMhL4mbpcWcIq1Rs2nLSE3JviE/dCG5mhQGw2M= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Andrew Fasano , Florian Westphal , Sasha Levin Subject: [PATCH 6.18 154/175] netfilter: nf_tables: fix inverted genmask check in nft_map_catchall_activate() Date: Mon, 9 Feb 2026 15:23:47 +0100 Message-ID: <20260209142326.036670828@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260209142320.474120190@linuxfoundation.org> References: <20260209142320.474120190@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andrew Fasano [ Upstream commit f41c5d151078c5348271ffaf8e7410d96f2d82f8 ] nft_map_catchall_activate() has an inverted element activity check compared to its non-catchall counterpart nft_mapelem_activate() and compared to what is logically required. nft_map_catchall_activate() is called from the abort path to re-activate catchall map elements that were deactivated during a failed transaction. It should skip elements that are already active (they don't need re-activation) and process elements that are inactive (they need to be restored). Instead, the current code does the opposite: it skips inactive elements and processes active ones. Compare the non-catchall activate callback, which is correct: nft_mapelem_activate(): if (nft_set_elem_active(ext, iter->genmask)) return 0; /* skip active, process inactive */ With the buggy catchall version: nft_map_catchall_activate(): if (!nft_set_elem_active(ext, genmask)) continue; /* skip inactive, process active */ The consequence is that when a DELSET operation is aborted, nft_setelem_data_activate() is never called for the catchall element. For NFT_GOTO verdict elements, this means nft_data_hold() is never called to restore the chain->use reference count. Each abort cycle permanently decrements chain->use. Once chain->use reaches zero, DELCHAIN succeeds and frees the chain while catchall verdict elements still reference it, resulting in a use-after-free. This is exploitable for local privilege escalation from an unprivileged user via user namespaces + nftables on distributions that enable CONFIG_USER_NS and CONFIG_NF_TABLES. Fix by removing the negation so the check matches nft_mapelem_activate(): skip active elements, process inactive ones. Fixes: 628bd3e49cba ("netfilter: nf_tables: drop map element references from preparation phase") Signed-off-by: Andrew Fasano Signed-off-by: Florian Westphal Signed-off-by: Sasha Levin --- net/netfilter/nf_tables_api.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 3cbf2573b9e90..6059a299004d4 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -5917,7 +5917,7 @@ static void nft_map_catchall_activate(const struct nft_ctx *ctx, list_for_each_entry(catchall, &set->catchall_list, list) { ext = nft_set_elem_ext(set, catchall->elem); - if (!nft_set_elem_active(ext, genmask)) + if (nft_set_elem_active(ext, genmask)) continue; nft_clear(ctx->net, ext); -- 2.51.0