mirror of
https://gitlab.torproject.org/tpo/core/tor.git
synced 2024-12-06 19:41:15 +01:00
Nick Mathewson
96d2a21683
Right-shifting negative values has implementation-defined behavior.
On all the platforms we work on right now, the behavior is to
sign-extend the input. That isn't what we wanted in
auth_type_val = (descriptor_cookie_tmp[16] >> 4) + 1;
Fix for 6861; bugfix on 0.2.1.5-alpha; reported pseudonymously.
The broken behavior didn't actually hurt anything, I think, since the
only way to get sign-extension to happen would be to have the top bit
of descriptor_cookie_tmp[16] set, which would make the value of
descriptor_cookie_tmp[16] >> 4 somewhere between 0b11111111 and
0b11111000 (that is, between -1 and -8). So auth_type_val would be
between -7 and 0. And the immediate next line does:
if (auth_type_val < 1 || auth_type_val > 2) {
So the incorrectly computed auth_type_val would be rejected as
invalid, just as a correctly computed auth_type_val would be.
Still, this stuff shouldn't sit around the codebase.
Tor protects your privacy on the internet by hiding the connection
between your Internet address and the services you use. We believe Tor
is reasonably secure, but please ensure you read the instructions and
configure it properly.
To build Tor from source:
./configure && make && make install
Home page:
https://www.torproject.org/
Download new versions:
https://www.torproject.org/download.html
Documentation, including links to installation and setup instructions:
https://www.torproject.org/documentation.html
Making applications work with Tor:
https://wiki.torproject.org/noreply/TheOnionRouter/TorifyHOWTO
Frequently Asked Questions:
https://www.torproject.org/faq.html
https://wiki.torproject.org/noreply/TheOnionRouter/TorFAQ