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openSUSE:Leap:15.5:Update
qemu.23275
tftp-introduce-a-header-structure.patch
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File tftp-introduce-a-header-structure.patch of Package qemu.23275
From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= <marcandre.lureau@redhat.com> Date: Fri, 4 Jun 2021 20:01:20 +0400 Subject: tftp: introduce a header structure MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Git-commit: 990163cf3ac86b7875559f49602c4d76f46f6f30 References: bsc#1187366, CVE-2021-3595 Instead of using a composed structure and potentially reading past the incoming buffer, use a different structure for the header. Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> Signed-off-by: Jose R Ziviani <jose.ziviani@suse.com> --- src/tftp.c | 60 ++++++++++++++++++++++++++++-------------------------- src/tftp.h | 6 +++++- 2 files changed, 36 insertions(+), 30 deletions(-) diff --git a/slirp/src/tftp.c b/slirp/src/tftp.c index 5a6279396684ef809742bbbd0ee3..42c6c7a23c3f8290bba52a9458e7 100644 --- a/slirp/src/tftp.c +++ b/slirp/src/tftp.c @@ -50,7 +50,7 @@ static void tftp_session_terminate(struct tftp_session *spt) } static int tftp_session_allocate(Slirp *slirp, struct sockaddr_storage *srcsas, - struct tftp_t *tp) + struct tftphdr *hdr) { struct tftp_session *spt; int k; @@ -75,7 +75,7 @@ found: memcpy(&spt->client_addr, srcsas, sockaddr_size(srcsas)); spt->fd = -1; spt->block_size = 512; - spt->client_port = tp->udp.uh_sport; + spt->client_port = hdr->udp.uh_sport; spt->slirp = slirp; tftp_session_update(spt); @@ -84,7 +84,7 @@ found: } static int tftp_session_find(Slirp *slirp, struct sockaddr_storage *srcsas, - struct tftp_t *tp) + struct tftphdr *hdr) { struct tftp_session *spt; int k; @@ -94,7 +94,7 @@ static int tftp_session_find(Slirp *slirp, struct sockaddr_storage *srcsas, if (tftp_session_in_use(spt)) { if (sockaddr_equal(&spt->client_addr, srcsas)) { - if (spt->client_port == tp->udp.uh_sport) { + if (spt->client_port == hdr->udp.uh_sport) { return k; } } @@ -146,13 +146,13 @@ static struct tftp_t *tftp_prep_mbuf_data(struct tftp_session *spt, } static void tftp_udp_output(struct tftp_session *spt, struct mbuf *m, - struct tftp_t *recv_tp) + struct tftphdr *hdr) { if (spt->client_addr.ss_family == AF_INET6) { struct sockaddr_in6 sa6, da6; sa6.sin6_addr = spt->slirp->vhost_addr6; - sa6.sin6_port = recv_tp->udp.uh_dport; + sa6.sin6_port = hdr->udp.uh_dport; da6.sin6_addr = ((struct sockaddr_in6 *)&spt->client_addr)->sin6_addr; da6.sin6_port = spt->client_port; @@ -161,7 +161,7 @@ static void tftp_udp_output(struct tftp_session *spt, struct mbuf *m, struct sockaddr_in sa4, da4; sa4.sin_addr = spt->slirp->vhost_addr; - sa4.sin_port = recv_tp->udp.uh_dport; + sa4.sin_port = hdr->udp.uh_dport; da4.sin_addr = ((struct sockaddr_in *)&spt->client_addr)->sin_addr; da4.sin_port = spt->client_port; @@ -183,14 +183,14 @@ static int tftp_send_oack(struct tftp_session *spt, const char *keys[], tp = tftp_prep_mbuf_data(spt, m); - tp->tp_op = htons(TFTP_OACK); + tp->hdr.tp_op = htons(TFTP_OACK); for (i = 0; i < nb; i++) { n += slirp_fmt0(tp->x.tp_buf + n, sizeof(tp->x.tp_buf) - n, "%s", keys[i]); n += slirp_fmt0(tp->x.tp_buf + n, sizeof(tp->x.tp_buf) - n, "%u", values[i]); } - m->m_len = G_SIZEOF_MEMBER(struct tftp_t, tp_op) + n; - tftp_udp_output(spt, m, recv_tp); + m->m_len = G_SIZEOF_MEMBER(struct tftp_t, hdr.tp_op) + n; + tftp_udp_output(spt, m, &recv_tp->hdr); return 0; } @@ -211,21 +211,21 @@ static void tftp_send_error(struct tftp_session *spt, uint16_t errorcode, tp = tftp_prep_mbuf_data(spt, m); - tp->tp_op = htons(TFTP_ERROR); + tp->hdr.tp_op = htons(TFTP_ERROR); tp->x.tp_error.tp_error_code = htons(errorcode); slirp_pstrcpy((char *)tp->x.tp_error.tp_msg, sizeof(tp->x.tp_error.tp_msg), msg); m->m_len = sizeof(struct tftp_t) - (TFTP_BLOCKSIZE_MAX + 2) + 3 + strlen(msg) - sizeof(struct udphdr); - tftp_udp_output(spt, m, recv_tp); + tftp_udp_output(spt, m, &recv_tp->hdr); out: tftp_session_terminate(spt); } static void tftp_send_next_block(struct tftp_session *spt, - struct tftp_t *recv_tp) + struct tftphdr *hdr) { struct mbuf *m; struct tftp_t *tp; @@ -239,7 +239,7 @@ static void tftp_send_next_block(struct tftp_session *spt, tp = tftp_prep_mbuf_data(spt, m); - tp->tp_op = htons(TFTP_DATA); + tp->hdr.tp_op = htons(TFTP_DATA); tp->x.tp_data.tp_block_nr = htons((spt->block_nr + 1) & 0xffff); nobytes = tftp_read_data(spt, spt->block_nr, tp->x.tp_data.tp_buf, @@ -257,7 +257,7 @@ static void tftp_send_next_block(struct tftp_session *spt, m->m_len = sizeof(struct tftp_t) - (TFTP_BLOCKSIZE_MAX - nobytes) - sizeof(struct udphdr); - tftp_udp_output(spt, m, recv_tp); + tftp_udp_output(spt, m, hdr); if (nobytes == spt->block_size) { tftp_session_update(spt); @@ -280,12 +280,12 @@ static void tftp_handle_rrq(Slirp *slirp, struct sockaddr_storage *srcsas, int nb_options = 0; /* check if a session already exists and if so terminate it */ - s = tftp_session_find(slirp, srcsas, tp); + s = tftp_session_find(slirp, srcsas, &tp->hdr); if (s >= 0) { tftp_session_terminate(&slirp->tftp_sessions[s]); } - s = tftp_session_allocate(slirp, srcsas, tp); + s = tftp_session_allocate(slirp, srcsas, &tp->hdr); if (s < 0) { return; @@ -411,29 +411,29 @@ static void tftp_handle_rrq(Slirp *slirp, struct sockaddr_storage *srcsas, } spt->block_nr = 0; - tftp_send_next_block(spt, tp); + tftp_send_next_block(spt, &tp->hdr); } static void tftp_handle_ack(Slirp *slirp, struct sockaddr_storage *srcsas, - struct tftp_t *tp, int pktlen) + struct tftphdr *hdr) { int s; - s = tftp_session_find(slirp, srcsas, tp); + s = tftp_session_find(slirp, srcsas, hdr); if (s < 0) { return; } - tftp_send_next_block(&slirp->tftp_sessions[s], tp); + tftp_send_next_block(&slirp->tftp_sessions[s], hdr); } static void tftp_handle_error(Slirp *slirp, struct sockaddr_storage *srcsas, - struct tftp_t *tp, int pktlen) + struct tftphdr *hdr) { int s; - s = tftp_session_find(slirp, srcsas, tp); + s = tftp_session_find(slirp, srcsas, hdr); if (s < 0) { return; @@ -444,23 +444,25 @@ static void tftp_handle_error(Slirp *slirp, struct sockaddr_storage *srcsas, void tftp_input(struct sockaddr_storage *srcsas, struct mbuf *m) { - struct tftp_t *tp = mtod_check(m, offsetof(struct tftp_t, x.tp_buf)); + struct tftphdr *hdr = mtod_check(m, sizeof(struct tftphdr)); - if (tp == NULL) { + if (hdr == NULL) { return; } - switch (ntohs(tp->tp_op)) { + switch (ntohs(hdr->tp_op)) { case TFTP_RRQ: - tftp_handle_rrq(m->slirp, srcsas, tp, m->m_len); + tftp_handle_rrq(m->slirp, srcsas, + mtod(m, struct tftp_t *), + m->m_len); break; case TFTP_ACK: - tftp_handle_ack(m->slirp, srcsas, tp, m->m_len); + tftp_handle_ack(m->slirp, srcsas, hdr); break; case TFTP_ERROR: - tftp_handle_error(m->slirp, srcsas, tp, m->m_len); + tftp_handle_error(m->slirp, srcsas, hdr); break; } } diff --git a/slirp/src/tftp.h b/slirp/src/tftp.h index c47bb43c7d0875e0df5fa50d6ed3..021f6cf109bca7dc17d3b30fa6e9 100644 --- a/slirp/src/tftp.h +++ b/slirp/src/tftp.h @@ -18,9 +18,13 @@ #define TFTP_FILENAME_MAX 512 #define TFTP_BLOCKSIZE_MAX 1428 -struct tftp_t { +struct tftphdr { struct udphdr udp; uint16_t tp_op; +} SLIRP_PACKED; + +struct tftp_t { + struct tftphdr hdr; union { struct { uint16_t tp_block_nr;
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