Hogweed needs nettle, not the other way around. So make sure they
are specified in the correct order for the static link to succeed.
(cherry picked from commit 5ef3a70d1d)
Our fast paths assume that each channel fits in to a separate byte.
That means the shift needs to be a multiple of 8. Start actually
checking this so that a client cannot trip us up and possibly cause
incorrect code exection.
Issue found by Pavel Cheremushkin from Kaspersky Lab.
(cherry picked from commit 05e2849087)
We use a lot of lengths given to us over the network, so be more
paranoid about them causing an overflow as otherwise an attacker
might trick us in to overwriting other memory.
This primarily affects the client which often gets lengths from the
server, but there are also some scenarios where the server might
theoretically be vulnerable.
Issue found by Pavel Cheremushkin from Kaspersky Lab.
(cherry picked from commit 75e6e0653a)
Provides safety against them accidentally becoming negative because
of bugs in the calculations.
Also does the same to CharArray and friends as they were strongly
connection to the stream objects.
(cherry picked from commit 0943c006c7)
Otherwise we might be tricked in to reading and writing things at
incorrect offsets for pixels which ultimately could result in an
attacker writing things to the stack or heap and executing things
they shouldn't.
This only affects the server as the client never uses the pixel
format suggested by th server.
Issue found by Pavel Cheremushkin from Kaspersky Lab.
(cherry picked from commit cd1d650c53)
We always assumed there would be one pixel per row so a rect with
a zero width would result in us writing to unknown memory.
This could theoretically be used by a malicious server to inject
code in to the viewer process.
Issue found by Pavel Cheremushkin from Kaspersky Lab.
(cherry picked from commit b4ada8d0c6)
No one should every try to write to this buffer. Enforce that by
throwing an exception if any one tries to get a writeable pointer
to the data.
(cherry picked from commit 9f615301ab)
We do a lot of calculations based on pixel coordinates and we need
to make sure they do not overflow. Restrict the maximum dimensions
we support rather than try to switch over all calculations to use
64 bit integers.
This prevents attackers from from injecting code by specifying a
huge framebuffer size and relying on the values overflowing to
access invalid areas of the heap.
This primarily affects the client which gets both the screen
dimensions and the pixel contents from the remote side. But the
server might also be affected as a client can adjust the screen
dimensions, as can applications inside the session.
Issue found by Pavel Cheremushkin from Kaspersky Lab.
(cherry picked from commit 996356b6c6)
Don't allow subclasses to just override dimensions or buffer details
directly and instead force them to go via methods. This allows us
to do sanity checks on the new values and catch bugs and attacks.
(cherry picked from commit 53f913a761)
Move the checks around to avoid missing cases where we might access
memory that is no longer valid. Also avoid touching the underlying
stream implicitly (e.g. via the destructor) as it might also no
longer be valid.
A malicious server could theoretically use this for remote code
execution in the client.
Issue found by Pavel Cheremushkin from Kaspersky Lab
(cherry picked from commit d61a767d68)
We need to check the buffer length before accessing the incoming
string. Probably not a problem in practice as there should be a
final null in most incoming strings.
Issue found by Pavel Cheremushkin from Kaspersky Lab.
Implements support in both client and server for the extended
clipboard format first seen in UltraVNC. Currently only implements
text handling, but that is still an improvement as it extends the
clipboard from ISO 8859-1 to full Unicode.