Fortunately, in 0.3.5.1-alpha we improved logging for various
failure cases involved with onion service client auth.
Unfortunately, for this one, we freed the file right before logging
its name.
Fortunately, tor_free() sets its pointer to NULL, so we didn't have
a use-after-free bug.
Unfortunately, passing NULL to %s is not defined.
Fortunately, GCC 9.1.1 caught the issue!
Unfortunately, nobody has actually tried building Tor with GCC 9.1.1
before. Or if they had, they didn't report the warning.
Fixes bug 30475; bugfix on 0.3.5.1-alpha.
In this patch we lower the log level of the failures for the three calls
to unlink() in networkstatus_set_current_consensus(). These errors might
trigger on Windows because the memory mapped consensus file keeps the
file in open state even after we have close()'d it. Windows will then
error on the unlink() call with a "Permission denied" error.
The consequences of ignoring these errors is that we leave an unused
file around on the file-system, which is an easier way to fix this
problem right now than refactoring networkstatus_set_current_consensus().
See: https://bugs.torproject.org/29930
We need to encode here instead of doing escaped(), since fwict
escaped() does not currently handle NUL bytes.
Also, use warn_if_nul_found in more cases to avoid duplication.
Unlike kill, timelimit can only signal the process it launches. So we need
timelimit to launch python, not make.
Closes ticket 30117; diagnostic for 29437.
The function compat_getdelim_ is used for tor_getline if tor is compiled
on a system that lacks getline and getdelim. These systems should be
very rare, considering that getdelim is POSIX.
If this system is further a 32 bit architecture, it is possible to
trigger a double free with huge files.
If bufsiz has been already increased to 2 GB, the next chunk would
be 4 GB in size, which wraps around to 0 due to 32 bit limitations.
A realloc(*buf, 0) could be imagined as "free(*buf); return malloc(0);"
which therefore could return NULL. The code in question considers
that an error, but will keep the value of *buf pointing to already
freed memory.
The caller of tor_getline() would free the pointer again, therefore
leading to a double free.
This code can only be triggered in dirserv_read_measured_bandwidths
with a huge measured bandwith list file on a system that actually
allows to reach 2 GB of space through realloc.
It is not possible to trigger this on Linux with glibc or other major
*BSD systems even on unit tests, because these systems cannot reach
so much memory due to memory fragmentation.
This patch is effectively based on the penetration test report of
cure53 for curl available at https://cure53.de/pentest-report_curl.pdf
and explained under section "CRL-01-007 Double-free in aprintf() via
unsafe size_t multiplication (Medium)".
George Kadianakis
Nick Mathewson
Karsten Loesing
Alexander Færøy
teor
Tobias Stoeckmann
rl1987