From 9c443ac4559a47ed99859bd80d14dc4b6dd220a1 Mon Sep 17 00:00:00 2001 From: Arjun Shankar Date: Tue, 2 Aug 2022 11:10:25 +0200 Subject: socket: Check lengths before advancing pointer in CMSG_NXTHDR The inline and library functions that the CMSG_NXTHDR macro may expand to increment the pointer to the header before checking the stride of the increment against available space. Since C only allows incrementing pointers to one past the end of an array, the increment must be done after a length check. This commit fixes that and includes a regression test for CMSG_FIRSTHDR and CMSG_NXTHDR. The Linux, Hurd, and generic headers are all changed. Tested on Linux on armv7hl, i686, x86_64, aarch64, ppc64le, and s390x. [BZ #28846] Reviewed-by: Siddhesh Poyarekar --- socket/tst-cmsghdr-skeleton.c | 92 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 92 insertions(+) create mode 100644 socket/tst-cmsghdr-skeleton.c (limited to 'socket/tst-cmsghdr-skeleton.c') diff --git a/socket/tst-cmsghdr-skeleton.c b/socket/tst-cmsghdr-skeleton.c new file mode 100644 index 0000000000..4c6898569b --- /dev/null +++ b/socket/tst-cmsghdr-skeleton.c @@ -0,0 +1,92 @@ +/* Test ancillary data header creation. + Copyright (C) 2022 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +/* We use the preprocessor to generate the function/macro tests instead of + using indirection because having all the macro expansions alongside + each other lets the compiler warn us about suspicious pointer + arithmetic across subsequent CMSG_{FIRST,NXT}HDR expansions. */ + +#include + +#define RUN_TEST_CONCAT(suffix) run_test_##suffix +#define RUN_TEST_FUNCNAME(suffix) RUN_TEST_CONCAT (suffix) + +static void +RUN_TEST_FUNCNAME (CMSG_NXTHDR_IMPL) (void) +{ + struct msghdr m = {0}; + struct cmsghdr *cmsg; + char cmsgbuf[3 * CMSG_SPACE (sizeof (PAYLOAD))] = {0}; + + m.msg_control = cmsgbuf; + m.msg_controllen = sizeof (cmsgbuf); + + /* First header should point to the start of the buffer. */ + cmsg = CMSG_FIRSTHDR (&m); + TEST_VERIFY_EXIT ((char *) cmsg == cmsgbuf); + + /* If the first header length consumes the entire buffer, there is no + space remaining for additional headers. */ + cmsg->cmsg_len = sizeof (cmsgbuf); + cmsg = CMSG_NXTHDR_IMPL (&m, cmsg); + TEST_VERIFY_EXIT (cmsg == NULL); + + /* The first header length is so big, using it would cause an overflow. */ + cmsg = CMSG_FIRSTHDR (&m); + TEST_VERIFY_EXIT ((char *) cmsg == cmsgbuf); + cmsg->cmsg_len = SIZE_MAX; + cmsg = CMSG_NXTHDR_IMPL (&m, cmsg); + TEST_VERIFY_EXIT (cmsg == NULL); + + /* The first header leaves just enough space to hold another header. */ + cmsg = CMSG_FIRSTHDR (&m); + TEST_VERIFY_EXIT ((char *) cmsg == cmsgbuf); + cmsg->cmsg_len = sizeof (cmsgbuf) - sizeof (struct cmsghdr); + cmsg = CMSG_NXTHDR_IMPL (&m, cmsg); + TEST_VERIFY_EXIT (cmsg != NULL); + + /* The first header leaves space but not enough for another header. */ + cmsg = CMSG_FIRSTHDR (&m); + TEST_VERIFY_EXIT ((char *) cmsg == cmsgbuf); + cmsg->cmsg_len ++; + cmsg = CMSG_NXTHDR_IMPL (&m, cmsg); + TEST_VERIFY_EXIT (cmsg == NULL); + + /* The second header leaves just enough space to hold another header. */ + cmsg = CMSG_FIRSTHDR (&m); + TEST_VERIFY_EXIT ((char *) cmsg == cmsgbuf); + cmsg->cmsg_len = CMSG_LEN (sizeof (PAYLOAD)); + cmsg = CMSG_NXTHDR_IMPL (&m, cmsg); + TEST_VERIFY_EXIT (cmsg != NULL); + cmsg->cmsg_len = sizeof (cmsgbuf) + - CMSG_SPACE (sizeof (PAYLOAD)) /* First header. */ + - sizeof (struct cmsghdr); + cmsg = CMSG_NXTHDR_IMPL (&m, cmsg); + TEST_VERIFY_EXIT (cmsg != NULL); + + /* The second header leaves space but not enough for another header. */ + cmsg = CMSG_FIRSTHDR (&m); + TEST_VERIFY_EXIT ((char *) cmsg == cmsgbuf); + cmsg = CMSG_NXTHDR_IMPL (&m, cmsg); + TEST_VERIFY_EXIT (cmsg != NULL); + cmsg->cmsg_len ++; + cmsg = CMSG_NXTHDR_IMPL (&m, cmsg); + TEST_VERIFY_EXIT (cmsg == NULL); + + return; +} -- cgit v1.2.3