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libslirp/0006-tftp-introduce-a-header-structure.patch
Marc-André Lureau 091d374633 Fix CVE-2021-3592 CVE-2021-3593 CVE-2021-3594 CVE-2021-3595 out-of-bounds access 
Resolves: rhbz#1970826
Resolves: rhbz#1970839
Resolves: rhbz#1970857
Resolves: rhbz#1970847
2021-06-18 17:14:15 +04:00

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From c8665ebbdadb72f7c2cb74b9704f68704c13653b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= <marcandre.lureau@redhat.com>
Date: Fri, 4 Jun 2021 20:01:20 +0400
Subject: [PATCH 6/7] tftp: introduce a header structure
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
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>
(cherry picked from commit 990163cf3ac86b7875559f49602c4d76f46f6f30)
---
src/tftp.c | 60 ++++++++++++++++++++++++++++--------------------------
src/tftp.h | 6 +++++-
2 files changed, 36 insertions(+), 30 deletions(-)
diff --git a/src/tftp.c b/src/tftp.c
index e06911d..a19c889 100644
--- a/src/tftp.c
+++ b/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;
}
}
@@ -148,13 +148,13 @@ 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;
@@ -163,7 +163,7 @@ 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;
@@ -185,14 +185,14 @@ 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;
}
@@ -213,21 +213,21 @@ 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;
@@ -241,7 +241,7 @@ 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,
@@ -259,7 +259,7 @@ 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);
@@ -282,12 +282,12 @@ 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;
@@ -413,29 +413,29 @@ 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;
@@ -446,23 +446,25 @@ 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/src/tftp.h b/src/tftp.h
index 6d75478..cafab03 100644
--- a/src/tftp.h
+++ b/src/tftp.h
@@ -20,9 +20,13 @@
#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;
--
2.29.0
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