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 87BEE1CD3F for ; Fri, 14 Mar 2025 12:42:40 +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=1741956163; cv=none; b=MFdw+ddaytqmCIEz/3rjKehrLGHauzVgFCXebQyzz8ZIQj3s4uogpDS4YfUObICb7UZ2d09EefNHGt580yDF05Vh/ja6P17+iKJgC4+RYCf9M+wpYjBcOzFwGiiMbAWiH4jhNI8TgJYrXU0tAF8bP4ZxO8P4N05ragPsMm8vbDU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741956163; c=relaxed/simple; bh=iD+MgR69CoDyku/9TsJF6tBuNK3jCMEv/I5vWM+HX4U=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=OlHAwwgjoW8AMxpmRJZkbc0DN/Z+GtrA+ZATMUIBWODgdTLNa20YwbrePjRQ955jWlfFkgSUCr6QMB6i9j8WRGCS6s/nTmdTppeJ9WrrfQ/U0V25QWDyIhK5WBb1TdeEGjAzxHV5Z98HqLB204PRjOWlFbDaeLo8tyy/GvLhhoE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=strlen.de; spf=pass smtp.mailfrom=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=breakpoint.cc Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1tt4N4-0006a2-FX; Fri, 14 Mar 2025 13:42:38 +0100 From: Florian Westphal To: netfilter-devel@vger.kernel.org Cc: Florian Westphal Subject: [PATCH nft] netlink: fix stack buffer overrun when emitting ranged expressions Date: Fri, 14 Mar 2025 13:41:49 +0100 Message-ID: <20250314124159.2131-1-fw@strlen.de> X-Mailer: git-send-email 2.45.3 Precedence: bulk X-Mailing-List: netfilter-devel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Included bogon input generates following Sanitizer splat: AddressSanitizer: dynamic-stack-buffer-overflow on address 0x7... WRITE of size 2 at 0x7fffffffcbe4 thread T0 #0 0x0000003a68b8 in __asan_memset (src/nft+0x3a68b8) (BuildId: 3678ff51a5405c77e3e0492b9a985910efee73b8) #1 0x0000004eb603 in __mpz_export_data src/gmputil.c:108:2 #2 0x0000004eb603 in netlink_export_pad src/netlink.c:256:2 #3 0x0000004eb603 in netlink_gen_range src/netlink.c:471:2 #4 0x0000004ea250 in __netlink_gen_data src/netlink.c:523:10 #5 0x0000004e8ee3 in alloc_nftnl_setelem src/netlink.c:205:3 #6 0x0000004d4541 in mnl_nft_setelem_batch src/mnl.c:1816:11 Problem is that the range end is emitted to the buffer at the *padded* location (rounded up to next register size), but buffer sizing is based of the expression length, not the padded length. Also extend the test script: Capture stderr and if we see AddressSanitizer warning, make it fail. Same bug as the one fixed in 600b84631410 ("netlink: fix stack buffer overflow with sub-reg sized prefixes"), just in a different function. Apply same fix: no dynamic array + add a length check. Signed-off-by: Florian Westphal --- src/netlink.c | 11 +++++++---- tests/shell/testcases/bogons/assert_failures | 17 ++++++++++++++++- ...an_stack_buffer_overrun_in_netlink_gen_range | 6 ++++++ 3 files changed, 29 insertions(+), 5 deletions(-) create mode 100644 tests/shell/testcases/bogons/nft-f/asan_stack_buffer_overrun_in_netlink_gen_range diff --git a/src/netlink.c b/src/netlink.c index 8e6e2066fe2a..52c2d8009b82 100644 --- a/src/netlink.c +++ b/src/netlink.c @@ -462,11 +462,14 @@ static void netlink_gen_verdict(const struct expr *expr, static void netlink_gen_range(const struct expr *expr, struct nft_data_linearize *nld) { - unsigned int len = div_round_up(expr->left->len, BITS_PER_BYTE) * 2; - unsigned char data[len]; - unsigned int offset = 0; + unsigned int len = (netlink_padded_len(expr->left->len) / BITS_PER_BYTE) * 2; + unsigned char data[NFT_MAX_EXPR_LEN_BYTES]; + unsigned int offset; - memset(data, 0, len); + if (len > sizeof(data)) + BUG("Value export of %u bytes would overflow", len); + + memset(data, 0, sizeof(data)); offset = netlink_export_pad(data, expr->left->value, expr->left); netlink_export_pad(data + offset, expr->right->value, expr->right); nft_data_memcpy(nld, data, len); diff --git a/tests/shell/testcases/bogons/assert_failures b/tests/shell/testcases/bogons/assert_failures index 79099427c98a..3dee63b3f97b 100755 --- a/tests/shell/testcases/bogons/assert_failures +++ b/tests/shell/testcases/bogons/assert_failures @@ -1,12 +1,27 @@ #!/bin/bash dir=$(dirname $0)/nft-f/ +tmpfile=$(mktemp) + +cleanup() +{ + rm -f "$tmpfile" +} + +trap cleanup EXIT for f in $dir/*; do - $NFT --check -f "$f" + echo "Check $f" + $NFT --check -f "$f" 2> "$tmpfile" if [ $? -ne 1 ]; then echo "Bogus input file $f did not cause expected error code" 1>&2 exit 111 fi + + if grep AddressSanitizer "$tmpfile"; then + echo "Address sanitizer splat for $f" 1>&2 + cat "$tmpfile" + exit 111 + fi done diff --git a/tests/shell/testcases/bogons/nft-f/asan_stack_buffer_overrun_in_netlink_gen_range b/tests/shell/testcases/bogons/nft-f/asan_stack_buffer_overrun_in_netlink_gen_range new file mode 100644 index 000000000000..2f7872e4accd --- /dev/null +++ b/tests/shell/testcases/bogons/nft-f/asan_stack_buffer_overrun_in_netlink_gen_range @@ -0,0 +1,6 @@ +table ip test { + chain y { + redirect to :tcp dport map { 83 : 80/3, 84 :4 } + } +} + -- 2.45.3