(S)ProcXIBarrierReleasePointer
[jcristau: originally this patch fixed the same issue as commit
211e05ac85 "Xi: Test exact size of XIBarrierReleasePointer", with the
addition of these checks]
This addresses CVE-2017-12179
v2: Add overflow check and remove unnecessary check (Julien Cristau)
This addresses:
CVE-2017-12184 in XINERAMA
CVE-2017-12185 in MIT-SCREEN-SAVER
CVE-2017-12186 in X-Resource
CVE-2017-12187 in RENDER
A client can send a big request where the 32B "length" field has value
0. When the big request header is removed and the length corrected,
the value will underflow to 0xFFFFFFFF. Functions processing the
request later will think that the client sent much more data and may
touch memory beyond the receive buffer.
Generating strings for XKB data used a single shared static buffer,
which offered several opportunities for errors. Use a ring of
resizable buffers instead, to avoid problems when strings end up
longer than anticipated.
XkbStringText escapes non-printable characters using octal numbers.
Such escape sequence would be at most 5 characters long ("\0123"), so
it reserves 5 bytes in the buffer. Due to char->unsigned int
conversion, it would print much longer string for negative numbers.
Otherwise it can belong to a non-existing client and abort X server with
FatalError "client not in use", or overwrite existing segment of another
existing client.
Without the checks a malformed PCF file can cause the library to make
atom from random heap memory that was behind the `strings` buffer.
This may crash the process or leak information.
This prevents a malicious user logging out from calling
chmod while still owning /dev/console and thus by-passing
the '622' mode that is set here.
Issue reported by Tim Chase. Thanks.
Merged from xdm upstreams
stsp@ reported that modesetting(4) has been reported unreliable
on his laptop, while intel(4) works.
XXXX to be removed after 6.2 to figure out and fix the issue.
ok kettenis@, also discussed briefly with deraadt@ during EuroBSDCon.
prefer DISPLAY=unix:0 rather than DISPLAY=:0.
This will prevent applications from ever falling back to TCP if the
UNIX socket connection fails (such as when the X server crashes).
joint work with tb@
cluebat and ok matthieu@
require python/bison a configure flag instead of the previous way of
testing whether python was found (which shouldn't be the case in
xenocara even with ports packages installed).
This is required when timestamps change on files causing targets to be
invoked that will break if python and bison aren't available and found
in path by the configure script.
It is supposed to be slow, and when such instructions are used to copy
data from/to mapped video memory, some hypervisors (e.g. KVM,
Microsoft Hyper-V) can generate SIGILL or SIGBUS exceptions, causing
Xorg to crash.
Bug report to OpenBSD by Max Parmer, fix from FreeBSD (Dimitry Andric)
via kettenis@
ok kettenis@
