The 'refresh_rrset' variable is used to determine if we can detach from
the client. This can cause a hang on shutdown. To fix this, move setting
of the 'nodetach' variable up to where 'refresh_rrset' is set (in
query_lookup(), and thus not in ns_query_done()), and set it to false
when actually refreshing the RRset, so that when this lookup is
completed, the client will be detached.
When a query was aborted because of the recursion quota being exceeded,
but triggered a stale answer response and a stale data refresh query,
it could cause named to loop back where we are iterating and following
a delegation. Having no good answer in cache, we would fall back to
using serve-stale again, use the stale data, try to refresh the RRset,
and loop back again, without ever terminating until crashing due to
stack overflow.
This happens because in the functions 'query_notfound()' and
'query_delegation_recurse()', we check whether we can fall back to
serving stale data. We shouldn't do so if we are already refreshing
an RRset due to having prioritized stale data in cache.
In other words, we need to add an extra check to 'query_usestale()' to
disallow serving stale data if we are currently refreshing a stale
RRset.
As an additional mitigation to prevent looping, we now use the result
code ISC_R_ALREADYRUNNING rather than ISC_R_FAILURE when a recursion
loop is encountered, and we check for that condition in
'query_usestale()' as well.
When cache memory usage is over the configured cache size (overmem) and
we are cleaning unused entries, it might not be enough to clean just two
entries if the entries to be expired are smaller than the newly added
rdata. This could be abused by an attacker to cause a remote Denial of
Service by possibly running out of the operating system memory.
Currently, the addrdataset() tries to do a single TTL-based cleaning
considering the serve-stale TTL and then optionally moves to overmem
cleaning if we are in that condition. Then the overmem_purge() tries to
do another single TTL based cleaning from the TTL heap and then continue
with LRU-based cleaning up to 2 entries cleaned.
Squash the TTL-cleaning mechanism into single call from addrdataset(),
but ignore the serve-stale TTL if we are currently overmem.
Then instead of having a fixed number of entries to clean, pass the size
of newly added rdatasetheader to the overmem_purge() function and
cleanup at least the size of the newly added data. This prevents the
cache going over the configured memory limit (`max-cache-size`).
Additionally, refactor the overmem_purge() function to reduce for-loop
nesting for readability.
The $t1 value equals $t2 due to the time elapsed between "rndc
managed-keys status" calls being equal to the normal active refresh
period (as calculated per rules listed in RFC 5011 section 2.3) minus an
"hour" (as set using -T mkeytimers). This value equality is expected to
happen on really slow machines. On our Windows CI runner, it happens
very often.
Fedora 38 and Debian "bullseye" images were "forked" to images used only
for TSAN CI jobs. The new images contain TSAN-aware liburcu that does
not fit well with ASAN CI jobs for which original images were also used.
liburcu is not used in this branch, but images are shared among
branches, and their use needs to be consistent in all maintained
branches.
(cherry picked from commit 04dda8661f)
We recently fixed a bug where in some cases (when following an
expired CNAME for example), named could return SERVFAIL if the target
record is still valid (see isc-projects/bind9#3678, and
isc-projects/bind9!7096). We fixed this by considering non-stale
RRsets as well during the stale lookup.
However, this triggered a new bug because despite the answer from
cache not being stale, the lookup may be triggered by serve-stale.
If the answer from database is not stale, the fix in
isc-projects/bind9!7096 erroneously skips the serve-stale logic.
Add 'answer_found' checks to the serve-stale logic to fix this issue.
(cherry picked from commit bbd163acf6)
Add a test case where when priming the cache with a slow authoritative
resolver, the stale-answer-client-timeout option should not return
a delegation to the client (it should wait until an applicable answer
is found, if no entry is found in the cache).
(cherry picked from commit c3d4fd3449)
All but the "respdiff-long" job, for which our AWS instances do not have
enough memory, are now being spawned in the AWS by the autoscaler
executor.
(cherry picked from commit f09cf69594)
The line summarising TSAN reports was misplaced in the ASAN territory
and thus never used.
I also made core dumps, assertion failures, and TSAN reports detection
independent of each other.
(cherry picked from commit 0c4c7ddec4)
This check is too unstable on Windows. Given the bind-9.16 branch is in
security fixes-only mode, something unlikely to be investigated before
the branch goes EOL.
Constructors and destructors for the main program are not reliable
as they may be called before constructors for shared libraries they
depend upon or be called after destructors of shared libraries they
depend upon.
The whole line needs to be read rather than just the token "nameserver"
otherwise the next line in resolv.conf is not properly processed.
(cherry picked from commit 864cd08052)
The zone_resigninc() function does not check the validity of
'zone->db', which can crash named if the zone was unloaded earlier,
for example with "rndc delete".
Check that 'zone->db' is not 'NULL' before attaching to it, like
it is done in zone_sign() and zone_nsec3chain() functions, which
can similarly be called by zone maintenance.
(cherry picked from commit fae0930eb8)
