From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 1503244CF44; Tue, 16 Jun 2026 15:55:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781625352; cv=none; b=A8xR6ZZH/bFBv6BZd0fJCZc/jUev0EwfYIRVir+4kj7rC5BVW1ZDFMzXyg/WNnfNNSWi2Mdce1OFJkHQCohJhH/zCZBe3bIuchrB+31GNgIE3eKOlaq/k6dL6KwpTohAoMROFDbpioBMDYQA13Ne8W4t0ZikV9GGO/Xl1y2gdYA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781625352; c=relaxed/simple; bh=e4lTl9LbAh0aEDSQBhP2y9UEtAV0WG29TVZb5b/w1fI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ZsGmo+tFnYt/JAfzT4d95xAH+/oqYmgAkuMPBhsIB7neLRDrZhmDaFvSapnkNsNbgKkEDxtiT31QM9UmBzBihYgOXhEPPEf+katlyBU8NBGPFH71j13MbxAldM0gGb+S32Fxu4e7SUfv/AukOIFLhNmZ9Frxrl1ObaEvJefQ1vk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=JTyYbwfp; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="JTyYbwfp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A25871F000E9; Tue, 16 Jun 2026 15:55:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1781625350; bh=1gp9VBybFUez6Po7dX0ttaOR6EURLWz6ktngZ0oaRAw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=JTyYbwfpSFhx+C4AGBPKGLSiHkvMVBXOfZ6WbJe/YNlAZ0hUjM2UyHNeAnjIHw/8T VDhng4qDgakW/suG5eHUOu7nIFpde4HaWGkx2KwbAkqhYQfEH0Lmad5nd3Ze0iyqVx DGg4gygOWGudp5jPZtD09aWfJW3hOrsd5pQxn4WU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kyle Zeng , Pablo Neira Ayuso , Sasha Levin Subject: [PATCH 6.18 126/325] netfilter: x_tables: avoid leaking percpu counter pointers Date: Tue, 16 Jun 2026 20:28:42 +0530 Message-ID: <20260616145103.994995161@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260616145057.827196531@linuxfoundation.org> References: <20260616145057.827196531@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev 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: Kyle Zeng [ Upstream commit f7f2fbb0e893a0238dc464f8d8c0f5609bec584f ] The native and compat get-entries paths copy the fixed rule entry header from the kernelized rule blob to userspace before overwriting the entry's counter fields with a sanitized counter snapshot. On SMP kernels, entry->counters.pcnt contains the percpu allocation address used by x_tables rule counters. A caller can provide a userspace buffer that faults during the initial fixed-header copy after pcnt has been copied but before the later sanitized counter copy runs. The syscall then returns -EFAULT while leaving the raw percpu pointer in userspace. Copy only the fixed entry prefix before counters from the kernelized rule blob, then copy the sanitized counter snapshot into the counter field. Apply this ordering to the IPv4, IPv6, and ARP native and compat get-entries implementations so a fault cannot expose the internal percpu counter pointer. Fixes: 71ae0dff02d7 ("netfilter: xtables: use percpu rule counters") Signed-off-by: Kyle Zeng Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin --- net/ipv4/netfilter/arp_tables.c | 15 ++++++--------- net/ipv4/netfilter/ip_tables.c | 15 ++++++--------- net/ipv6/netfilter/ip6_tables.c | 15 ++++++--------- 3 files changed, 18 insertions(+), 27 deletions(-) diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c index f3dadbc416a3a5..1490466b146e4b 100644 --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -702,14 +702,12 @@ static int copy_entries_to_user(unsigned int total_size, const struct xt_entry_target *t; e = loc_cpu_entry + off; - if (copy_to_user(userptr + off, e, sizeof(*e))) { - ret = -EFAULT; - goto free_counters; - } - if (copy_to_user(userptr + off + if (copy_to_user(userptr + off, e, + offsetof(struct arpt_entry, counters)) || + copy_to_user(userptr + off + offsetof(struct arpt_entry, counters), &counters[num], - sizeof(counters[num])) != 0) { + sizeof(counters[num]))) { ret = -EFAULT; goto free_counters; } @@ -1327,9 +1325,8 @@ static int compat_copy_entry_to_user(struct arpt_entry *e, void __user **dstptr, origsize = *size; ce = *dstptr; - if (copy_to_user(ce, e, sizeof(struct arpt_entry)) != 0 || - copy_to_user(&ce->counters, &counters[i], - sizeof(counters[i])) != 0) + if (copy_to_user(ce, e, offsetof(struct compat_arpt_entry, counters)) || + copy_to_user(&ce->counters, &counters[i], sizeof(counters[i]))) return -EFAULT; *dstptr += sizeof(struct compat_arpt_entry); diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c index f4079f0718deae..0549fad53c0364 100644 --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -832,14 +832,12 @@ copy_entries_to_user(unsigned int total_size, const struct xt_entry_target *t; e = loc_cpu_entry + off; - if (copy_to_user(userptr + off, e, sizeof(*e))) { - ret = -EFAULT; - goto free_counters; - } - if (copy_to_user(userptr + off + if (copy_to_user(userptr + off, e, + offsetof(struct ipt_entry, counters)) || + copy_to_user(userptr + off + offsetof(struct ipt_entry, counters), &counters[num], - sizeof(counters[num])) != 0) { + sizeof(counters[num]))) { ret = -EFAULT; goto free_counters; } @@ -1228,9 +1226,8 @@ compat_copy_entry_to_user(struct ipt_entry *e, void __user **dstptr, origsize = *size; ce = *dstptr; - if (copy_to_user(ce, e, sizeof(struct ipt_entry)) != 0 || - copy_to_user(&ce->counters, &counters[i], - sizeof(counters[i])) != 0) + if (copy_to_user(ce, e, offsetof(struct compat_ipt_entry, counters)) || + copy_to_user(&ce->counters, &counters[i], sizeof(counters[i]))) return -EFAULT; *dstptr += sizeof(struct compat_ipt_entry); diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c index dfaea4f6727ed9..3586e636c66bdc 100644 --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -848,14 +848,12 @@ copy_entries_to_user(unsigned int total_size, const struct xt_entry_target *t; e = loc_cpu_entry + off; - if (copy_to_user(userptr + off, e, sizeof(*e))) { - ret = -EFAULT; - goto free_counters; - } - if (copy_to_user(userptr + off + if (copy_to_user(userptr + off, e, + offsetof(struct ip6t_entry, counters)) || + copy_to_user(userptr + off + offsetof(struct ip6t_entry, counters), &counters[num], - sizeof(counters[num])) != 0) { + sizeof(counters[num]))) { ret = -EFAULT; goto free_counters; } @@ -1244,9 +1242,8 @@ compat_copy_entry_to_user(struct ip6t_entry *e, void __user **dstptr, origsize = *size; ce = *dstptr; - if (copy_to_user(ce, e, sizeof(struct ip6t_entry)) != 0 || - copy_to_user(&ce->counters, &counters[i], - sizeof(counters[i])) != 0) + if (copy_to_user(ce, e, offsetof(struct compat_ip6t_entry, counters)) || + copy_to_user(&ce->counters, &counters[i], sizeof(counters[i]))) return -EFAULT; *dstptr += sizeof(struct compat_ip6t_entry); -- 2.53.0