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libnv: fix heap overflow in nvlist_recv()

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nvlist_check_header() validated nvlh_size for overflow before
performing conversion. An mallicous user can set
NV_FLAG_BIG_ENDIAN in the header and craft nvlh_size so that
the orginall value passes the check, but after the conversion the
sizeof(nvlist_header) + size can overflow.
This can lead to a heap buffer overflow.

Approved by:	so
Security:	FreeBSD-SA-26:17.libnv
Security:	CVE-2026-35547
Fixes:		36fa90dbde0060aacb5677d0b113ee168e839071
Reviewed by:	markj
Differential Revision:	https://reviews.freebsd.org/D56342
This commit is contained in:
Mariusz Zaborski 2026-04-28 14:36:09 +00:00 committed by Franco Fichtner
parent 4b28a8af30
commit 7b7e6d7376
2 changed files with 62 additions and 4 deletions
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57
lib/libnv/tests/nvlist_send_recv_test.c
View file

@ -1,5 +1,8 @@
/*-
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2013 The FreeBSD Foundation
* Copyright (c) 2024-2026 Mariusz Zaborski <oshogbo@FreeBSD.org>
*
* This software was developed by Pawel Jakub Dawidek under sponsorship from
* the FreeBSD Foundation.
@ -664,6 +667,58 @@ ATF_TC_BODY(nvlist_send_recv__overflow_header_size, tc)
}
}
ATF_TC_WITHOUT_HEAD(nvlist_send_recv__overflow_big_endian_size);
ATF_TC_BODY(nvlist_send_recv__overflow_big_endian_size, tc)
{
static const unsigned char payload[] = {
0x6c, /* magic */
0x00, /* version */
0x80, /* flags: NV_FLAG_BIG_ENDIAN */
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf5,
};
nvlist_t *nvl;
int sv[2];
ATF_REQUIRE_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sv), 0);
ATF_REQUIRE_EQ(write(sv[1], payload, sizeof(payload)),
(ssize_t)sizeof(payload));
ATF_REQUIRE_EQ(close(sv[1]), 0);
errno = 0;
nvl = nvlist_recv(sv[0], 0);
ATF_REQUIRE(nvl == NULL);
ATF_REQUIRE_EQ(errno, EINVAL);
ATF_REQUIRE_EQ(close(sv[0]), 0);
}
ATF_TC_WITHOUT_HEAD(nvlist_send_recv__overflow_little_endian_size);
ATF_TC_BODY(nvlist_send_recv__overflow_little_endian_size, tc)
{
static const unsigned char payload[] = {
0x6c, /* magic */
0x00, /* version */
0x00, /* flags */
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0xf5, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
};
nvlist_t *nvl;
int sv[2];
ATF_REQUIRE_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sv), 0);
ATF_REQUIRE_EQ(write(sv[1], payload, sizeof(payload)),
(ssize_t)sizeof(payload));
ATF_REQUIRE_EQ(close(sv[1]), 0);
errno = 0;
nvl = nvlist_recv(sv[0], 0);
ATF_REQUIRE(nvl == NULL);
ATF_REQUIRE_EQ(errno, EINVAL);
ATF_REQUIRE_EQ(close(sv[0]), 0);
}
ATF_TC_WITHOUT_HEAD(nvlist_send_recv__invalid_fd_size);
ATF_TC_BODY(nvlist_send_recv__invalid_fd_size, tc)
{
@ -799,6 +854,8 @@ ATF_TP_ADD_TCS(tp)
ATF_TP_ADD_TC(tp, nvlist_send_recv__send_many_fds__stream);
ATF_TP_ADD_TC(tp, nvlist_send_recv__overflow_header_size);
ATF_TP_ADD_TC(tp, nvlist_send_recv__overflow_big_endian_size);
ATF_TP_ADD_TC(tp, nvlist_send_recv__overflow_little_endian_size);
ATF_TP_ADD_TC(tp, nvlist_send_recv__invalid_fd_size);
ATF_TP_ADD_TC(tp, nvlist_send_recv__overflow_fd_size);

9
sys/contrib/libnv/nvlist.c
View file

@ -1022,10 +1022,6 @@ static bool
nvlist_check_header(struct nvlist_header *nvlhdrp)
{
if (nvlhdrp->nvlh_size > SIZE_MAX - sizeof(*nvlhdrp)) {
ERRNO_SET(EINVAL);
return (false);
}
if (nvlhdrp->nvlh_magic != NVLIST_HEADER_MAGIC) {
ERRNO_SET(EINVAL);
return (false);
@ -1045,6 +1041,11 @@ nvlist_check_header(struct nvlist_header *nvlhdrp)
nvlhdrp->nvlh_descriptors = be64toh(nvlhdrp->nvlh_descriptors);
}
#endif
if (nvlhdrp->nvlh_size > SIZE_MAX - sizeof(*nvlhdrp)) {
ERRNO_SET(EINVAL);
return (false);
}
return (true);
}