From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [91.216.245.30]) (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 191053C0A04; Thu, 2 Jul 2026 10:51:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.216.245.30 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782989462; cv=none; b=lTTzG/FWLUFpCvYdmoIGcXNlyGrUzZtZfMXtIRowxI8zB2rS5jDr20mWPX2I4m6BpTRbOTLJCX2buUiAJfgn4vn11zZTlwV/+1hl7ynUAgAtQKccxG2T+BQG8keaEf0p+y+liPn/aC7W6jLmc284bbesq/LSyRaKrFRSr4VJpAU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782989462; c=relaxed/simple; bh=CDs2WiizyhC7fea+Ua2oM6fnOg+EaDQ6hBs+/Tps8pI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Ty7xlU5+JibDMEoRyELVRijY32dftJYx/gI6DlLvRGu6EOJh4vdC41Iu44dl3RgaN4pdF1nkZx2M+LoVlJbUKKwJD5udmnkXk3INMnqYPiltpeR9fEFv+Rw4EcZ6HrfXS/yzhoE1StKMjmfkB0l79f5DaBjR9d+h3LD+FO6xXD4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=strlen.de; spf=pass smtp.mailfrom=Chamillionaire.breakpoint.cc; arc=none smtp.client-ip=91.216.245.30 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=strlen.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=Chamillionaire.breakpoint.cc Received: by Chamillionaire.breakpoint.cc (Postfix, from userid 1003) id 9017060687; Thu, 02 Jul 2026 12:50:59 +0200 (CEST) From: Florian Westphal To: Cc: Paolo Abeni , "David S. Miller" , Eric Dumazet , Jakub Kicinski , , pablo@netfilter.org Subject: [PATCH net-next 11/12] netfilter: ebtables: bound num_counters like nentries in do_replace() Date: Thu, 2 Jul 2026 12:50:02 +0200 Message-ID: <20260702105003.13550-12-fw@strlen.de> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260702105003.13550-1-fw@strlen.de> References: <20260702105003.13550-1-fw@strlen.de> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jiayuan Chen do_replace_finish() allocates the counter buffer before it is validated: counterstmp = vmalloc_array(repl->num_counters, sizeof(*counterstmp)); do_replace() only checks num_counters against INT_MAX / sizeof(struct ebt_counter), so vmalloc_array() can be asked for up to 134217726 * 16 = 2147483616 bytes (~2 GiB). num_counters must in fact equal nentries: do_replace_finish() later rejects the request when repl->num_counters != t->private->nentries. get_counters() folds the per-CPU counters back into one entry per rule, so what userspace gets is bounded by nentries, never by nentries * nr_cpus. Apply the same upper bound used for nentries (MAX_EBT_ENTRIES) to the incoming num_counters so the over-sized allocation can no longer be requested. The allocation is still kept outside the ebt_mutex, since vmalloc() may sleep and trigger reclaim; only the bound is tightened. Signed-off-by: Jiayuan Chen Signed-off-by: Florian Westphal --- net/bridge/netfilter/ebtables.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c index f20c039e44c8..042d31278713 100644 --- a/net/bridge/netfilter/ebtables.c +++ b/net/bridge/netfilter/ebtables.c @@ -39,6 +39,8 @@ #define COUNTER_OFFSET(n) (SMP_ALIGN(n * sizeof(struct ebt_counter))) #define COUNTER_BASE(c, n, cpu) ((struct ebt_counter *)(((char *)c) + \ COUNTER_OFFSET(n) * cpu)) +#define MAX_EBT_ENTRIES (((INT_MAX - sizeof(struct ebt_table_info)) / \ + NR_CPUS - SMP_CACHE_BYTES) / sizeof(struct ebt_counter)) struct ebt_pernet { struct list_head tables; @@ -1124,10 +1126,9 @@ static int do_replace(struct net *net, sockptr_t arg, unsigned int len) return -EINVAL; /* overflow check */ - if (tmp.nentries >= ((INT_MAX - sizeof(struct ebt_table_info)) / - NR_CPUS - SMP_CACHE_BYTES) / sizeof(struct ebt_counter)) + if (tmp.nentries >= MAX_EBT_ENTRIES) return -ENOMEM; - if (tmp.num_counters >= INT_MAX / sizeof(struct ebt_counter)) + if (tmp.num_counters >= MAX_EBT_ENTRIES) return -ENOMEM; tmp.name[sizeof(tmp.name) - 1] = 0; @@ -2265,10 +2266,9 @@ static int compat_copy_ebt_replace_from_user(struct ebt_replace *repl, if (tmp.entries_size == 0) return -EINVAL; - if (tmp.nentries >= ((INT_MAX - sizeof(struct ebt_table_info)) / - NR_CPUS - SMP_CACHE_BYTES) / sizeof(struct ebt_counter)) + if (tmp.nentries >= MAX_EBT_ENTRIES) return -ENOMEM; - if (tmp.num_counters >= INT_MAX / sizeof(struct ebt_counter)) + if (tmp.num_counters >= MAX_EBT_ENTRIES) return -ENOMEM; memcpy(repl, &tmp, offsetof(struct ebt_replace, hook_entry)); -- 2.54.0