[pve-devel] [PATCH pve-qemu] slirp: re-add security patches
Oguz Bektas
o.bektas at proxmox.com
Wed Mar 11 15:57:42 CET 2020
the first two patches were mistakenly left out during the 4.2 qemu
rebase.
also adds another patch for issue CVE-2019-14378 (heap-based BOF)
Signed-off-by: Oguz Bektas <o.bektas at proxmox.com>
---
.../0001-util-add-slirp_fmt-helpers.patch | 126 ++++++++++++++++
...2-tcp_emu-fix-unsafe-snprintf-usages.patch | 135 ++++++++++++++++++
.../0003-ip_reass-Fix-use-after-free.patch | 46 ++++++
debian/patches/series | 4 +
4 files changed, 311 insertions(+)
create mode 100644 debian/patches/security/0001-util-add-slirp_fmt-helpers.patch
create mode 100644 debian/patches/security/0002-tcp_emu-fix-unsafe-snprintf-usages.patch
create mode 100644 debian/patches/security/0003-ip_reass-Fix-use-after-free.patch
diff --git a/debian/patches/security/0001-util-add-slirp_fmt-helpers.patch b/debian/patches/security/0001-util-add-slirp_fmt-helpers.patch
new file mode 100644
index 0000000..af944f8
--- /dev/null
+++ b/debian/patches/security/0001-util-add-slirp_fmt-helpers.patch
@@ -0,0 +1,126 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= <marcandre.lureau at redhat.com>
+Date: Mon, 27 Jan 2020 10:24:09 +0100
+Subject: [PATCH 1/2] util: add slirp_fmt() helpers
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Various calls to snprintf() in libslirp assume that snprintf() returns
+"only" the number of bytes written (excluding terminating NUL).
+
+https://pubs.opengroup.org/onlinepubs/9699919799/functions/snprintf.html#tag_16_159_04
+
+"Upon successful completion, the snprintf() function shall return the
+number of bytes that would be written to s had n been sufficiently
+large excluding the terminating null byte."
+
+Introduce slirp_fmt() that handles several pathological cases the
+way libslirp usually expect:
+
+- treat error as fatal (instead of silently returning -1)
+
+- fmt0() will always \0 end
+
+- return the number of bytes actually written (instead of what would
+have been written, which would usually result in OOB later), including
+the ending \0 for fmt0()
+
+- warn if truncation happened (instead of ignoring)
+
+Other less common cases can still be handled with strcpy/snprintf() etc.
+
+Signed-off-by: Marc-André Lureau <marcandre.lureau at redhat.com>
+Reviewed-by: Samuel Thibault <samuel.thibault at ens-lyon.org>
+Message-Id: <20200127092414.169796-2-marcandre.lureau at redhat.com>
+Signed-off-by: Oguz Bektas <o.bektas at proxmox.com>
+---
+ slirp/src/util.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ slirp/src/util.h | 3 +++
+ 2 files changed, 65 insertions(+)
+
+diff --git a/slirp/src/util.c b/slirp/src/util.c
+index e596087..e3b6257 100644
+--- a/slirp/src/util.c
++++ b/slirp/src/util.c
+@@ -364,3 +364,65 @@ void slirp_pstrcpy(char *buf, int buf_size, const char *str)
+ }
+ *q = '\0';
+ }
++
++static int slirp_vsnprintf(char *str, size_t size,
++ const char *format, va_list args)
++{
++ int rv = vsnprintf(str, size, format, args);
++
++ if (rv < 0) {
++ g_error("vsnprintf() failed: %s", g_strerror(errno));
++ }
++
++ return rv;
++}
++
++/*
++ * A snprintf()-like function that:
++ * - returns the number of bytes written (excluding optional \0-ending)
++ * - dies on error
++ * - warn on truncation
++ */
++int slirp_fmt(char *str, size_t size, const char *format, ...)
++{
++ va_list args;
++ int rv;
++
++ va_start(args, format);
++ rv = slirp_vsnprintf(str, size, format, args);
++ va_end(args);
++
++ if (rv > size) {
++ g_critical("vsnprintf() truncation");
++ }
++
++ return MIN(rv, size);
++}
++
++/*
++ * A snprintf()-like function that:
++ * - always \0-end (unless size == 0)
++ * - returns the number of bytes actually written, including \0 ending
++ * - dies on error
++ * - warn on truncation
++ */
++int slirp_fmt0(char *str, size_t size, const char *format, ...)
++{
++ va_list args;
++ int rv;
++
++ va_start(args, format);
++ rv = slirp_vsnprintf(str, size, format, args);
++ va_end(args);
++
++ if (rv >= size) {
++ g_critical("vsnprintf() truncation");
++ if (size > 0)
++ str[size - 1] = '\0';
++ rv = size;
++ } else {
++ rv += 1; /* include \0 */
++ }
++
++ return rv;
++}
+diff --git a/slirp/src/util.h b/slirp/src/util.h
+index 3c6223c..0558dfc 100644
+--- a/slirp/src/util.h
++++ b/slirp/src/util.h
+@@ -177,4 +177,7 @@ static inline int slirp_socket_set_fast_reuse(int fd)
+
+ void slirp_pstrcpy(char *buf, int buf_size, const char *str);
+
++int slirp_fmt(char *str, size_t size, const char *format, ...);
++int slirp_fmt0(char *str, size_t size, const char *format, ...);
++
+ #endif
+--
+2.20.1
+
diff --git a/debian/patches/security/0002-tcp_emu-fix-unsafe-snprintf-usages.patch b/debian/patches/security/0002-tcp_emu-fix-unsafe-snprintf-usages.patch
new file mode 100644
index 0000000..099fecd
--- /dev/null
+++ b/debian/patches/security/0002-tcp_emu-fix-unsafe-snprintf-usages.patch
@@ -0,0 +1,135 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= <marcandre.lureau at redhat.com>
+Date: Mon, 27 Jan 2020 10:24:14 +0100
+Subject: [PATCH 2/2] tcp_emu: fix unsafe snprintf() usages
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Various calls to snprintf() assume that snprintf() returns "only" the
+number of bytes written (excluding terminating NUL).
+
+https://pubs.opengroup.org/onlinepubs/9699919799/functions/snprintf.html#tag_16_159_04
+
+"Upon successful completion, the snprintf() function shall return the
+number of bytes that would be written to s had n been sufficiently
+large excluding the terminating null byte."
+
+Before patch ce131029, if there isn't enough room in "m_data" for the
+"DCC ..." message, we overflow "m_data".
+
+After the patch, if there isn't enough room for the same, we don't
+overflow "m_data", but we set "m_len" out-of-bounds. The next time an
+access is bounded by "m_len", we'll have a buffer overflow then.
+
+Use slirp_fmt*() to fix potential OOB memory access.
+
+Reported-by: Laszlo Ersek <lersek at redhat.com>
+Signed-off-by: Marc-André Lureau <marcandre.lureau at redhat.com>
+Reviewed-by: Samuel Thibault <samuel.thibault at ens-lyon.org>
+Message-Id: <20200127092414.169796-7-marcandre.lureau at redhat.com>
+Signed-off-by: Oguz Bektas <o.bektas at proxmox.com>
+---
+ slirp/src/tcp_subr.c | 44 +++++++++++++++++++++-----------------------
+ 1 file changed, 21 insertions(+), 23 deletions(-)
+
+diff --git a/slirp/src/tcp_subr.c b/slirp/src/tcp_subr.c
+index d6dd133..93b3488 100644
+--- a/slirp/src/tcp_subr.c
++++ b/slirp/src/tcp_subr.c
+@@ -655,8 +655,7 @@ int tcp_emu(struct socket *so, struct mbuf *m)
+ NTOHS(n1);
+ NTOHS(n2);
+ m_inc(m, snprintf(NULL, 0, "%d,%d\r\n", n1, n2) + 1);
+- m->m_len = snprintf(m->m_data, M_ROOM(m), "%d,%d\r\n", n1, n2);
+- assert(m->m_len < M_ROOM(m));
++ m->m_len = slirp_fmt(m->m_data, M_ROOM(m), "%d,%d\r\n", n1, n2);
+ } else {
+ *eol = '\r';
+ }
+@@ -696,9 +695,9 @@ int tcp_emu(struct socket *so, struct mbuf *m)
+ n4 = (laddr & 0xff);
+
+ m->m_len = bptr - m->m_data; /* Adjust length */
+- m->m_len += snprintf(bptr, m->m_size - m->m_len,
+- "ORT %d,%d,%d,%d,%d,%d\r\n%s", n1, n2, n3, n4,
+- n5, n6, x == 7 ? buff : "");
++ m->m_len += slirp_fmt(bptr, M_FREEROOM(m),
++ "ORT %d,%d,%d,%d,%d,%d\r\n%s",
++ n1, n2, n3, n4, n5, n6, x == 7 ? buff : "");
+ return 1;
+ } else if ((bptr = (char *)strstr(m->m_data, "27 Entering")) != NULL) {
+ /*
+@@ -731,11 +730,9 @@ int tcp_emu(struct socket *so, struct mbuf *m)
+ n4 = (laddr & 0xff);
+
+ m->m_len = bptr - m->m_data; /* Adjust length */
+- m->m_len +=
+- snprintf(bptr, m->m_size - m->m_len,
+- "27 Entering Passive Mode (%d,%d,%d,%d,%d,%d)\r\n%s",
+- n1, n2, n3, n4, n5, n6, x == 7 ? buff : "");
+-
++ m->m_len += slirp_fmt(bptr, M_FREEROOM(m),
++ "27 Entering Passive Mode (%d,%d,%d,%d,%d,%d)\r\n%s",
++ n1, n2, n3, n4, n5, n6, x == 7 ? buff : "");
+ return 1;
+ }
+
+@@ -758,8 +755,8 @@ int tcp_emu(struct socket *so, struct mbuf *m)
+ if (m->m_data[m->m_len - 1] == '\0' && lport != 0 &&
+ (so = tcp_listen(slirp, INADDR_ANY, 0, so->so_laddr.s_addr,
+ htons(lport), SS_FACCEPTONCE)) != NULL)
+- m->m_len =
+- snprintf(m->m_data, m->m_size, "%d", ntohs(so->so_fport)) + 1;
++ m->m_len = slirp_fmt0(m->m_data, M_ROOM(m),
++ "%d", ntohs(so->so_fport));
+ return 1;
+
+ case EMU_IRC:
+@@ -778,9 +775,10 @@ int tcp_emu(struct socket *so, struct mbuf *m)
+ return 1;
+ }
+ m->m_len = bptr - m->m_data; /* Adjust length */
+- m->m_len += snprintf(bptr, m->m_size, "DCC CHAT chat %lu %u%c\n",
+- (unsigned long)ntohl(so->so_faddr.s_addr),
+- ntohs(so->so_fport), 1);
++ m->m_len += slirp_fmt(bptr, M_FREEROOM(m),
++ "DCC CHAT chat %lu %u%c\n",
++ (unsigned long)ntohl(so->so_faddr.s_addr),
++ ntohs(so->so_fport), 1);
+ } else if (sscanf(bptr, "DCC SEND %256s %u %u %u", buff, &laddr, &lport,
+ &n1) == 4) {
+ if ((so = tcp_listen(slirp, INADDR_ANY, 0, htonl(laddr),
+@@ -788,10 +786,10 @@ int tcp_emu(struct socket *so, struct mbuf *m)
+ return 1;
+ }
+ m->m_len = bptr - m->m_data; /* Adjust length */
+- m->m_len +=
+- snprintf(bptr, m->m_size, "DCC SEND %s %lu %u %u%c\n", buff,
+- (unsigned long)ntohl(so->so_faddr.s_addr),
+- ntohs(so->so_fport), n1, 1);
++ m->m_len += slirp_fmt(bptr, M_FREEROOM(m),
++ "DCC SEND %s %lu %u %u%c\n", buff,
++ (unsigned long)ntohl(so->so_faddr.s_addr),
++ ntohs(so->so_fport), n1, 1);
+ } else if (sscanf(bptr, "DCC MOVE %256s %u %u %u", buff, &laddr, &lport,
+ &n1) == 4) {
+ if ((so = tcp_listen(slirp, INADDR_ANY, 0, htonl(laddr),
+@@ -799,10 +797,10 @@ int tcp_emu(struct socket *so, struct mbuf *m)
+ return 1;
+ }
+ m->m_len = bptr - m->m_data; /* Adjust length */
+- m->m_len +=
+- snprintf(bptr, m->m_size, "DCC MOVE %s %lu %u %u%c\n", buff,
+- (unsigned long)ntohl(so->so_faddr.s_addr),
+- ntohs(so->so_fport), n1, 1);
++ m->m_len += slirp_fmt(bptr, M_FREEROOM(m),
++ "DCC MOVE %s %lu %u %u%c\n", buff,
++ (unsigned long)ntohl(so->so_faddr.s_addr),
++ ntohs(so->so_fport), n1, 1);
+ }
+ return 1;
+
+--
+2.20.1
+
diff --git a/debian/patches/security/0003-ip_reass-Fix-use-after-free.patch b/debian/patches/security/0003-ip_reass-Fix-use-after-free.patch
new file mode 100644
index 0000000..86d2a71
--- /dev/null
+++ b/debian/patches/security/0003-ip_reass-Fix-use-after-free.patch
@@ -0,0 +1,46 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Samuel Thibault <samuel.thibault at ens-lyon.org>
+Date: Mon, 26 Aug 2019 00:55:03 +0200
+Subject: [PATCH] ip_reass: Fix use after free
+
+Using ip_deq after m_free might read pointers from an allocation reuse.
+
+This would be difficult to exploit, but that is still related with
+CVE-2019-14378 which generates fragmented IP packets that would trigger this
+issue and at least produce a DoS.
+
+Signed-off-by: Samuel Thibault <samuel.thibault at ens-lyon.org>
+(cherry picked from commit c59279437eda91841b9d26079c70b8a540d41204)
+Signed-off-by: Oguz Bektas <o.bektas at proxmox.com>
+---
+ src/ip_input.c | 6 ++++--
+ 1 file changed, 4 insertions(+), 2 deletions(-)
+
+diff --git a/slirp/src/ip_input.c b/slirp/src/ip_input.c
+index 8c75d91..c07d7d4 100644
+--- a/slirp/src/ip_input.c
++++ b/slirp/src/ip_input.c
+@@ -292,6 +292,7 @@ static struct ip *ip_reass(Slirp *slirp, struct ip *ip, struct ipq *fp)
+ */
+ while (q != (struct ipasfrag *)&fp->frag_link &&
+ ip->ip_off + ip->ip_len > q->ipf_off) {
++ struct ipasfrag *prev;
+ i = (ip->ip_off + ip->ip_len) - q->ipf_off;
+ if (i < q->ipf_len) {
+ q->ipf_len -= i;
+@@ -299,9 +300,10 @@ static struct ip *ip_reass(Slirp *slirp, struct ip *ip, struct ipq *fp)
+ m_adj(dtom(slirp, q), i);
+ break;
+ }
++ prev = q;
+ q = q->ipf_next;
+- m_free(dtom(slirp, q->ipf_prev));
+- ip_deq(q->ipf_prev);
++ ip_deq(prev);
++ m_free(dtom(slirp, prev));
+ }
+
+ insert:
+--
+2.20.1
+
diff --git a/debian/patches/series b/debian/patches/series
index 651c609..63598ab 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -30,3 +30,7 @@ pve/0029-PVE-Backup-add-vma-backup-format-code.patch
pve/0030-PVE-Backup-add-backup-dump-block-driver.patch
pve/0031-PVE-Backup-proxmox-backup-patches-for-qemu.patch
pve/0032-PVE-Backup-pbs-restore-new-command-to-restore-from-p.patch
+security/0001-util-add-slirp_fmt-helpers.patch
+security/0002-tcp_emu-fix-unsafe-snprintf-usages.patch
+security/0003-ip_reass-Fix-use-after-free.patch
+security/0004-tcp_emu-Fix-oob-access.patch
--
2.20.1
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