They are not allowed in the specification, and can lead to infinite
loops when parsing.
That’s a security issue if your application is accepting D-Bus messages
from untrusted peers (perhaps in a peer-to-peer connection). It’s not
exploitable when your application is connected to a bus (such as the
system or session buses), as the bus daemons (dbus-daemon or
dbus-broker) filter out such broken messages and don’t forward them.
Arrays of zero-length elements are disallowed in the D-Bus
specification: https://dbus.freedesktop.org/doc/dbus-specification.html#container-types
oss-fuzz#41428, #41435Fixes: #2557
The code in `g_dbus_message_new_from_blob()` has now been fixed to
correctly error out on all truncated messages, so there’s no need for an
arbitrary programmer error if the input is too short to contain a valid
D-Bus message header.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Helps: #2528
Perform strict bounds checking when reading data from the D-Bus message,
and propagate errors to the callers.
Previously, truncated D-Bus messages could cause out-of-bounds reads.
This is a security issue, but one which is only exploitable when
communicating with an untrusted peer (who might send malicious
messages). Almost all D-Bus traffic is with a session or system bus,
where the dbus-daemon or dbus-broker is trusted, and is known to have
already rejected malformed (malicious) messages.
Accordingly, this is only exploitable with peer-to-peer D-Bus
conversations with an untrusted peer.
(Includes some minor cleanups from Philip Withnall.)
oss-fuzz#17408
Fixes: #2528
This is the result of checking each `Returns:` line in these files. I’ve
only considered nullability and not other (potentially missing or
incorrect) annotations.
Including suggestions by Simon McVittie.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Helps: #2227
In the D-Bus wire protocol, the handle type (G_VARIANT_TYPE_HANDLE, h)
is intended to be an index/pointer into the implementation's closest
equivalent of GUnixFDList: its numeric value has no semantic meaning
(in the same way that the numeric values of pointers have no semantic
meaning), but a handle with value n acts as a reference to the nth fd
in the fd list.
GDBus provides a fairly direct mapping from the wire protocol to the
C API, which makes it technically possible to attach and use fds
without ever referring to them in the message body, and some
GLib-centric D-Bus APIs rely on this.
However, the other major implementations of D-Bus (libdbus and sd-bus)
transparently replace file descriptors with handles when building
messages, and transparently replace handles with file descriptors when
parsing messages. This means they cannot implement D-Bus APIs that do
not follow the conventional meaning of handles as indexes/pointers into
an equivalent of GUnixFDList.
For interoperability, we should encourage D-Bus API designers to follow
the convention, even though code written against GDBus doesn't strictly
need to do so.
Signed-off-by: Simon McVittie <smcv@collabora.com>
This was mostly machine generated with the following command:
```
codespell \
--builtin clear,rare,usage \
--skip './po/*' --skip './.git/*' --skip './NEWS*' \
--write-changes .
```
using the latest git version of `codespell` as per [these
instructions](https://github.com/codespell-project/codespell#user-content-updating).
Then I manually checked each change using `git add -p`, made a few
manual fixups and dropped a load of incorrect changes.
There are still some outdated or loaded terms used in GLib, mostly to do
with git branch terminology. They will need to be changed later as part
of a wider migration of git terminology.
If I’ve missed anything, please file an issue!
Signed-off-by: Philip Withnall <withnall@endlessm.com>
This is the analogue of commit 7c4e6e9fbe, but applied to the
`GDBusMessage` parser, which does its own top-level parsing of the
variant format in D-Bus messages.
Previously, this code allowed arbitrary recursion of variant containers,
which could lead to a stack overflow. Now, that recursion is limited to
64 levels, as per the D-Bus specification:
https://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-marshaling-signature
This includes a new unit test.
oss-fuzz#14870
Signed-off-by: Philip Withnall <withnall@endlessm.com>
This mostly affects the 2.56 branch, but, given that GCC 9 is being
stricter about passing null string pointers to printf-like functions, it
might make sense to proactively fix such calls.
gdbusauth.c: In function '_g_dbus_auth_run_server':
gdbusauth.c:1302:11: error: '%s' directive argument is null
[-Werror=format-overflow=]
1302 | debug_print ("SERVER: WaitingForBegin, read '%s'",
line);
|
gdbusmessage.c: In function ‘g_dbus_message_to_blob’:
gdbusmessage.c:2730:30: error: ‘%s’ directive argument is null [-Werror=format-overflow=]
2730 | tupled_signature_str = g_strdup_printf ("(%s)", signature_str);
|
With the changes to limit GVariant type nesting (commit 7c4e6e9fbe),
it’s now possible to have a valid type signature which is not a valid
GVariant type when enclosed in parentheses (to make it a tuple).
Check for that when parsing the signature field in a D-Bus message.
Includes a unit test.
oss-fuzz#11120
Signed-off-by: Philip Withnall <withnall@endlessm.com>
The code was checking whether the signature provided by the blob was a
valid D-Bus signature — but that’s a superset of a valid GVariant type
string, since a D-Bus signature is zero or more complete types. A
GVariant type string is exactly one complete type.
This meant that a D-Bus message with a header field containing a variant
with an empty type signature (for example) could cause a critical
warning in the code parsing it.
Fix that by checking whether the string is a valid type string too.
Unit test included.
oss-fuzz#9810
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Parsing a D-Bus message with the signature field in the message header
of type other than ‘g’ (GVariant type signature) would cause a critical
warning. Instead, we should return a runtime error.
Includes a test.
oss-fuzz#9825
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Autoconf macro AC_HEADER_MAJOR doesn't define a macro in config.h when
major is defined in sys/types.h. This was not a problem because major
is assumed to be always available. However, commit aefffa3fbc
changes this assumption in order to fix build on systems without major,
which causes code using major to be disabled on systems putting major
in sys/types.h.
This commit defines a new macro MAJOR_IN_TYPES for both autotools and
meson builds to make major useful on these systems again.
Apparently Solaris defines statbuf fields as long when Linux doesn’t, in
some cases. Cast down to the type expected by the printf() format
placeholder.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
https://bugzilla.gnome.org/show_bug.cgi?id=749652
Setting a variable and then assigning it to itself avoids
-Wunused-but-set-variable but this specific trick is now caught by
-Wself-assign. Instead, actually use the value or don't bother
assigning it at all:
gdbusauth.c: call g_data_input_stream_read_byte() in void context
gdbusauthmechanismsha1.c: value is actually used
gdbusmessage.c: use consistent preprocessor-token protection
gthreadedresolver.c: skip over bytes in data blob
httpd.c: do something useful with the value
https://bugzilla.gnome.org/show_bug.cgi?id=745723
Prevent the situation where errno is set by function A, then function B
is called (which is typically _(), but could be anything else) and it
overwrites errno, then errno is checked by the caller.
errno is a horrific API, and we need to be careful to save its value as
soon as a function call (which might set it) returns. i.e. Follow the
pattern:
int errsv, ret;
ret = some_call_which_might_set_errno ();
errsv = errno;
if (ret < 0)
puts (strerror (errsv));
This patch implements that pattern throughout GLib. There might be a few
places in the test code which still use errno directly. They should be
ported as necessary. It doesn’t modify all the call sites like this:
if (some_call_which_might_set_errno () && errno == ESOMETHING)
since the refactoring involved is probably more harmful than beneficial
there. It does, however, refactor other call sites regardless of whether
they were originally buggy.
https://bugzilla.gnome.org/show_bug.cgi?id=785577
It's unnecessary, and only adds visual noise; we have been fairly
inconsistent in the past, but the semi-colon-less version clearly
dominates in the code base.
https://bugzilla.gnome.org/show_bug.cgi?id=669355
If we have an input parameter (or return value) we need to use (nullable).
However, if it is an (inout) or (out) parameter, (optional) is sufficient.
It looks like (nullable) could be used for everything according to the
Annotation documentation, but (optional) is more specific.
If g_dbus_message_to_blob() fails at all, it will leak its mbuf. Spotted
by running the gdbus-serialization test under Valgrind — so there is a
justification for leak-free tests after all!
Fix a hang due to overflow by using unsigned numbers and explicitly
checking if the number overflows to zero. This also fixes the previous
logic which assigned an int which may be negative to an unsigned number
resulting in sign extension and strange results.
Use gsize rather than int to allow for large buffers on 64 bit machines.
https://bugzilla.gnome.org/show_bug.cgi?id=727988
It turns out that this bug actually would (sometimes) impact any sort of
fixed-sized array with an alignment requirement of 8 due to incorrectly
counting the alignment inserted between the (aligned 4) array length and
the actual data.
Fix this properly and remove the exception for doubles.
https://bugzilla.gnome.org/show_bug.cgi?id=732754
* removed passing GError to ensure_input_padding() function
- it was necessary before commit 3e5214c15c
when we used GData*Streams and GMemoryInputStream with
g_seekable_seek() - now it's useless,
* removed checking return value of ensure_input_padding()
function - in previous implementation (like above)
g_seekable_seek() could return FALSE - now it's always TRUE,
* removed passing GError to g_memory_buffer_read_*() functions
and checking returned value - it also has been inherited after
old implementation with g_data_input_stream_read_*() functions
- now it's also useless
* cleaned up code formatting,
https://bugzilla.gnome.org/show_bug.cgi?id=729875
