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-rw-r--r--main/dbus/CVE-2020-12049-part1.patch75
1 files changed, 75 insertions, 0 deletions
diff --git a/main/dbus/CVE-2020-12049-part1.patch b/main/dbus/CVE-2020-12049-part1.patch
new file mode 100644
index 0000000000..40b16c3f10
--- /dev/null
+++ b/main/dbus/CVE-2020-12049-part1.patch
@@ -0,0 +1,75 @@
+From 272d484283883fa9ff95b69d924fff6cd34842f5 Mon Sep 17 00:00:00 2001
+From: Simon McVittie <smcv@collabora.com>
+Date: Thu, 16 Apr 2020 14:45:11 +0100
+Subject: [PATCH] sysdeps-unix: On MSG_CTRUNC, close the fds we did receive
+
+MSG_CTRUNC indicates that we have received fewer fds that we should
+have done because the buffer was too small, but we were treating it
+as though it indicated that we received *no* fds. If we received any,
+we still have to make sure we close them, otherwise they will be leaked.
+
+On the system bus, if an attacker can induce us to leak fds in this
+way, that's a local denial of service via resource exhaustion.
+
+Reported-by: Kevin Backhouse, GitHub Security Lab
+Fixes: dbus#294
+Fixes: CVE-2020-12049
+Fixes: GHSL-2020-057
+---
+ dbus/dbus-sysdeps-unix.c | 32 ++++++++++++++++++++------------
+ 1 file changed, 20 insertions(+), 12 deletions(-)
+
+diff --git a/dbus/dbus-sysdeps-unix.c b/dbus/dbus-sysdeps-unix.c
+index e8cd5b33..f9dc2a6e 100644
+--- a/dbus/dbus-sysdeps-unix.c
++++ b/dbus/dbus-sysdeps-unix.c
+@@ -435,18 +435,6 @@ _dbus_read_socket_with_unix_fds (DBusSocket fd,
+ struct cmsghdr *cm;
+ dbus_bool_t found = FALSE;
+
+- if (m.msg_flags & MSG_CTRUNC)
+- {
+- /* Hmm, apparently the control data was truncated. The bad
+- thing is that we might have completely lost a couple of fds
+- without chance to recover them. Hence let's treat this as a
+- serious error. */
+-
+- errno = ENOSPC;
+- _dbus_string_set_length (buffer, start);
+- return -1;
+- }
+-
+ for (cm = CMSG_FIRSTHDR(&m); cm; cm = CMSG_NXTHDR(&m, cm))
+ if (cm->cmsg_level == SOL_SOCKET && cm->cmsg_type == SCM_RIGHTS)
+ {
+@@ -501,6 +489,26 @@ _dbus_read_socket_with_unix_fds (DBusSocket fd,
+ if (!found)
+ *n_fds = 0;
+
++ if (m.msg_flags & MSG_CTRUNC)
++ {
++ unsigned int i;
++
++ /* Hmm, apparently the control data was truncated. The bad
++ thing is that we might have completely lost a couple of fds
++ without chance to recover them. Hence let's treat this as a
++ serious error. */
++
++ /* We still need to close whatever fds we *did* receive,
++ * otherwise they'll never get closed. (CVE-2020-12049) */
++ for (i = 0; i < *n_fds; i++)
++ close (fds[i]);
++
++ *n_fds = 0;
++ errno = ENOSPC;
++ _dbus_string_set_length (buffer, start);
++ return -1;
++ }
++
+ /* put length back (doesn't actually realloc) */
+ _dbus_string_set_length (buffer, start + bytes_read);
+
+--
+2.26.2
+
+