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)".
If the concatenation of connection buffer and the buffer of linked
connection exceeds INT_MAX bytes, then buf_move_to_buf returns -1 as an
error value.
This value is currently casted to size_t (variable n_read) and will
erroneously lead to an increasement of variable "max_to_read".
This in turn can be used to call connection_buf_read_from_socket to
store more data inside the buffer than expected and clogging the
connection buffer.
If the linked connection buffer was able to overflow INT_MAX, the call
of buf_move_to_buf would have previously internally triggered an integer
overflow, corrupting the state of the connection buffer.
Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
Many buffer functions have a hard limit of INT_MAX for datalen, but
this limitation is not enforced in all functions:
- buf_move_all may exceed that limit with too many chunks
- buf_move_to_buf exceeds that limit with invalid buf_flushlen argument
- buf_new_with_data may exceed that limit (unit tests only)
This patch adds some annotations in some buf_pos_t functions to
guarantee that no out of boundary access could occur even if another
function lacks safe guards against datalen overflows.
Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
Fixes bug 29922; bugfix on 0.2.9.3-alpha when we tried to capture
all these warnings. No need to backport any farther than 0.3.5,
though -- these warnings don't cause test failures before then.
This one was tricky to find because apparently it only happened on
_some_ windows builds.
In current NSS versions, these ciphersuites don't work with
SSL_ExportKeyingMaterial(), which was causing relays to fail when
they tried to negotiate the v3 link protocol authentication.
Fixes bug 29241; bugfix on 0.4.0.1-alpha.
Nick Mathewson
George Kadianakis
Tobias Stoeckmann
teor
rl1987